EPA/600/R-14/031 | June 2014 | www.epa.gov/research
United States
Environmental Protection
Agency
Demonstration of
Innovative Sewer System
Inspection Technology: SL-RAT
Office of Research and Development
-------
EPA/600/R-14/031
June 2014
Demonstration of Innovative Sewer System
Inspection Technology:
SL-RAT™
By
Srinivas Panguluri
Shaw Environmental & Infrastructure, Inc.
Cincinnati, OH
Gary Skipper
Brown & Caldwell
San Diego, CA
Steve Donovan
Brown and Caldwell
Cincinnati, OH
Contract No. EP-C-11-006
Daniel Murray
Water Supply and Water Resources Division
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
National Risk Management Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
-------
Demonstration oj'SL-RAT™Report Notice
NOTICE
The U.S. Environmental Protection Agency (EPA), through its Office of Research and Development (ORD)
National Risk Management Research Laboratory (NRMRL) Water Supply and Water Resources Division
(WSWRD), funded and managed this technology demonstration through EPA Contract No. EP-C-11-006.
This report has been both peer and administratively reviewed and approved for publication as an EPA
document. Mention of trade names or commercial products does not constitute endorsement or
recommendation for use of a specific product.
Questions concerning this document or its application should be addressed to:
Daniel J. Murray, Jr., P.E.
Water Supply and Water Resources Division
National Risk Management Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
26 West Martin Luther King Dr.
Cincinnati, OH 45268
513-569-7522
murray.dan@epa.gov
-------
Demonstration oj'SL-RAT™Report Foreword
Foreword
The U.S. Environmental Protection Agency (EPA) was charged by Congress with protecting the Nation's
land, air, and water resources. Under a mandate of national environmental laws, EPA is tasked with
formulating and implementing actions leading to a compatible balance between human activities and
the ability of natural systems to support and nurture life. To help meet this mandate, EPA's research
program is providing data and technical support for solving environmental problems today and building
a science knowledge base necessary to protect human health and the environment.
The National Risk Management Research Laboratory (NRMRL) is the Agency's center for investigation of
technological and management approaches for preventing and reducing risks from pollution that
threaten human health and the environment. NRMRL's solution-based research program is focused on
(1) method and technology development and their cost effectiveness for prevention and control of
pollution to air, land, water, and subsurface resources; (2) protection of water quality in public water
systems; (3) remediation of contaminated sites, sediments, and groundwater; (4) prevention and control
of indoor air pollution; and (5) restoration of ecosystems.
This research provides solutions to environmental problems by developing and promoting technologies
that protect and improve the environment. NRMRL's research advances scientific and engineering
information to support regulatory and policy decisions, and provides the technical support and
information transfer to ensure implementation of environmental regulations and strategies at the
national, state, and community levels. NRMRL collaborates with both public and private sector partners
to anticipate emerging challenges and foster the development of technologies that reduce the cost of
regulatory compliance.
The information provided in this document will be of use to stakeholders such as state and federal
regulators, Native American tribes, consultants, contractors, and other interested parties.
Cynthia Sonich-Mullin, Director
National Risk Management Research Laboratory
-------
Demonstration ofSL-RA 7™ Report Abstract
Abstract
The overall objective of this EPA-funded study was to demonstrate innovative a sewer line assessment
technology that is designed for rapid deployment using portable equipment. This study focused on
demonstration of a technology that is suitable for smaller diameter pipes (less than 12-inch diameter).
The recently developed and commercially-available acoustic-based sewer pipe assessment technology
demonstrated during this study was the Sewer Line - Rapid Assessment Tool (SL-RAT™) manufactured
by InfoSense, Inc. (InfoSense) of North Carolina.
This technology can provide a rapid assessment of the need for pipe cleaning. Acoustic technologies
require a minimal amount of equipment when compared to traditional closed-circuit television (CCTV)
inspection systems. This acoustic based technology has the potential to provide information in a matter
of minutes to assist an operator in determining whether a sewer pipe might be partially or fully blocked
and require cleaning or renewal. The speed of the assessment, using minimal equipment, has the
potential to result in significant cost-savings compared to traditional methods, such as CCTV inspection.
It is generally known that smaller diameter pipes (i.e., less than or equal to 12-inch diameter) contribute
to over 90 percent of the sewer main backups reported in a typical city (Sprague, J., 2007). This study
hence focused on the demonstration of an acoustic technology that is suited for smaller diameter pipes.
This collaborative field demonstration of the SL-RAT was led by EPA's National Risk Management
Research Laboratory (NRMRL) in Cincinnati, Ohio. EPA worked with the Metropolitan Sewer District of
Greater Cincinnati (MSDGC) as a collaborative research partner to identify study locations, provide
access to the study area sewer lines and to perform the related field work. Specifically, the data and
information obtained from the following technologies were used in this demonstration project: SL-RAT;
Pan-Tilt-Zooming pole-mounted camera (aka "camera on a stick") manufactured by Envirosight
Quickview; and HD-digital scanning CCTV or the PANORAMO 3D Optical Pipeline Scanner manufactured
by RapidView-IBAK.
The results of this demonstration of the SL-RAT show promise for the application of this technology as a
tool for cost-effective, pre-cleaning assessment and post-cleaning quality assurance. The application of
this technology in an overall collection system O&M program should enable wastewater utilities to
optimize their sewer cleaning efforts and free up valuable resources to more effectively implement
critical CMOM and asset management programs.
-------
Demonstration oj'SL-RAT™ Report Table of Contents
Table of Contents
NOTICE i
FORWORD ii
ABSTRACT iii
TABLE OF CONTENTS iv
LIST OF TABLES vi
LIST OF FIGURES vi
ABBREVIATIONS & ACRONYMS vii
ACKNOWLEDGMENTS viii
EXECUTIVE SUMMARY ix
Section 1 —Introduction 1-1
1.1 Maintenance of Sanitary Sewers 1-1
1.2 Sewer Line Inspection Techniques 1-3
1.3 Industry Standard Sewer Inspection Methodology 1-5
1.4 Innovative Sewer Inspection Methodologies 1-6
1.5 Study Objective 1-7
1.6 SL-RAT Equipment Overview 1-7
1.7 Project Team 1-10
SECTION 2 —STUDY AREA DESCRIPTION AND EVALUATION PARAMETERS 2-1
2.1 Test Conditions 2-1
2.2 Condition Assessment/Inspection Strategy 2-2
2.3 CCTV and Pole Mounted Zooming Camera Data Evaluation Procedure 2-6
2.4 Rapid Deployment Evaluation Procedure 2-7
SECTION 3 —TECHNOLOGY DEMONSTRATION RESULTS 3-1
3.1 Galia Drive Study Area CCTV/SL-RAT Assessment Summary 3-1
3.1.1 Upper-Range Score Discussion 3-5
3.1.2 Medium-Range Score Discussion 3-5
3.1.3 Low-Range Score Discussion 3-6
3.2 Hunt Road Area CCTV/SL-RAT Assessment Summary 3-6
iv
-------
Demonstration oj'SL-RAT™ Report Table of Contents
3.3 Greenhills Area - Rapid Deployment Evaluation Summary 3-8
3.4 Miscellaneous Pipe Evaluation Summary 3-10
3.5 PACP and SL-RAT Score Correlation 3-10
3.6 SL-RAT Data Visualization and Post-Processing Tools 3-11
3.7 SL-RAT Operator Feedback 3-13
3.7.1 Usability 3-13
3.7.2 Data Quality 3-13
3.7.3 Software 3-13
SECTION 4 —SUMMARY AND CONCLUSIONS 4-1
4.1 Inspection Cost per Foot Analysis 4-2
4.2 Rapid Deployment Capability 4-5
4.3 Opportunity to Refocus Critical Resources Deployed for Pipe Cleaning 4-5
4.3.1 Routine Cleaning 4-5
4.3.2 Directed Cleaning 4-5
4.3.3 Reactive Cleaning 4-5
4.4 Conclusion 4-6
SECTION 5 —REFERENCES 5-1
APPENDIX A —SL-DOG CONDITION ASSESSMENT DATA VERIFICATION A-l
APPENDIX B —STUDY AREA FIGURES B-l
-------
Demonstration ofSL-RAT™ Report List of Tables & Figures
List of Tables
Table 1-1. Comparative SL-RATvs. CCTV Blockage Assessment 1-9
Table 2-1. Hunt Road, Galia Drive, and Greenhills Pipe Segment Size Summary 2-1
Table 2-2. Hunt Road, Galia Drive, and Greenhills Pipe Segment Material Summary 2-1
Table 3-1. Summary of SL-RAT and CCTV Results Galia Drive 3-2
Table 3-2. Summary of SL-RAT and CCTV Results Hunt Road 3-7
Table 3-3. Summary of Time Interval between Inspections for Greenhills 3-8
Table 3-4. Summary of SL-RAT Assessment Scores for Greenhills 3-9
Table 3-5. Summary of SL-RAT and CCTV Results Greenhills 3-9
Table 3-6. Example of PACP Assessment O&M Score - Galia Drive Data 3-10
Table 4-1. MSDGC On-Road CCTV Inspection Costs 4-2
Table 4-2. MSDGC Off-Road CCTV Inspection Costs 4-3
Table 4-3. SL-RAT On/Off-Road Inspection Costs 4-4
Table A-l. SL-RAT On/Off-Road Inspection Costs A-4
Table A-2. SL-RAT On/Off-Road Inspection Costs A-5
List of Figures
Figure 1-1. Custom Off-road CCTV Camera Tractor (Courtesy: MSDGC) 1-4
Figure 1-2. SL-RAT Conceptual Deployment 1-7
Figure 1-3. SL-RAT Deployment at EPA Project Site 1-8
Figure 2-1. Overall Test Procedure 2-3
Figure 2-2. Inspection Test Procedure 2-4
Figure 2-3. CCTV Test Procedure 2-5
Figure 3-1. Summary visual of SL-RAT Results Galia Drive 3-12
Figure 3-2. Typical Sound Pressure Level (SPL) Experienced by the SL-RAT Transmitter Operator
for Each One Second Tone 3-14
Figure 4-1. Sewer Pipe-Condition Assessment Tools (Adapted from: InfoSense, 2013) 4-1
Figure A-l. Five Galia road pipe segments used to illustrate the SL-RAT condition assessment
verification A-3
Figure A-2. GPS mapping for the three SL-RAT condition assessments conducted at Galia road
pipe segment 11706002-11707005 A-6
VI
-------
Demonstration oj'SL-RAT™Report
Abbreviations & Acronyms
Abbreviations & Acronyms
3-D Three-dimension
ADS ADS Environmental Services
ALSA ALSATechLLC
ATV All Terrain Vehicle
BC Brown and Caldwell
CCTV Closed-Circuit Television
CIP Cast Iron Pipe
CMOM Capacity, Management, Operation and Maintenance
CMU Charlotte Mecklenburg Utility
DIP Ductile Iron Pipe
EPA U.S. Environmental Protection Agency
GPS Global Positioning System
HD High-Definition
IBAK Ingenieur Buro Atlas, Kiel (manufacturer of RapidView and PANORAMO (CCTV))
l&l Infiltration and Inflow
MSDGC Metropolitan Sewer District of Greater Cincinnati
NASSCO National Association of Sewer Service Contractors
NRMRL National Risk Management Research Laboratory
O&M Operation and Maintenance
ORD Office of Research and Development
OSHA Occupational Safety & Health Adminstration
PACP Pipeline Assessment and Certification Program
PC Personal Computer
POTW Publicly Owned Treatment Works
PTSI Pegasus Technical Services, Inc.
PVC Poly-vinyl Chloride
QAPP Quality Assurance Project Plan
RCP Reinforced Concrete Pipe
RF Radio Frequencies
RX Receiver
SaaS software-as-a-service
SL-DOG Sewer Line Diagnostic OrGanizer
SL-RAT Sewer Line - Rapid Assessment Tool
SPL Sound Pressure Level
SSO Sanitary Sewer Overflow
TX Transmitter
USB Universal Serial Bus
USDOT United States Department of Transportation
VCP Vitrified Clay Pipe
WERF Water Environment Research Foundation
WSWRD Water Supply and Water Resources Division
VII
-------
Demonstration oj'SL-RAT™Report Acknowledgements
ACKNOWLEDGMENTS
Principal authors of this report:
United States Environmental Protection Agency
Daniel J. Murray, Jr., P.E.
Shaw Environmental & Infrastructure, Inc.
Srinivas Panguluri
Brown and Caldwell
Gary Skipper
Steve Donovan
Contributions of the following individuals and organizations that assisted in performing this
technology demonstration are gratefully acknowledged:
Metropolitan Sewer District of Greater Cincinnati
Jerry Weimer
Eric Schneider
Dustin Prue
Eric Withers
Mike Pittinger
InfoSense, Inc.
Ivan Howitt
Alex Churchill
ALSA Tech, LLC.
Abraham Chen
External technical peer reviewers:
CH2M Hill
Rick Nelson
Rick Arbour & Associates, Inc.
Rick Arbour
VIII
-------
Demonstration oj'SL-RAT™Report Executive Summary
Executive Summary
The focus on condition assessment of gravity wastewater collection systems (sewers) continues to
broaden. Traditionally, the main focus of condition assessment of sewers has been directed at
operational issues related to the collection and conveyance of flows to a facility for treatment and
disposal. To address operational issues, attention has tended to concentrate on maintenance activities
associated with the cleaning and removal of debris and foreign materials from collection system pipes.
The combination of debris and extraneous wet-weather induced flows can result in less than desired
levels of customer service and possibly cause raw sewage to overflow from the collection system or to
result in basement backups.
Cleaning and inspecting sewer pipes is essential for utilities to operate and maintain a properly
functioning system and minimize SSOs. The routine maintenance of a sewer system often includes sewer
system cleaning, root removal/treatment, and cleaning/clearing of sewer mainline blockages. However,
understanding where and when to perform cleaning activities in the most effective manner is not
necessarily a straight forward task. In an attempt to direct maintenance staff and cleaning equipment to
those pipes in a sewer system that require attention, some agencies identify cleaning needs by
conducting inspection of the sewers prior to cleaning. Rapid assessment approaches and tools provide
an avenue to significant pre-cleaning inspection cost savings that could be achieved through reduced
inspection and non-productive cleaning costs.
The overall objective of this EPA funded study was to demonstrate a recently developed innovative
acoustic-based sewer line assessment technology that is designed for rapid deployment using portable
equipment. This technology can provide a rapid assessment of the need for pipe cleaning and an overall
pipe-condition assessment. Acoustic technologies require a minimal amount of equipment when
compared to closed-circuit television (CCTV) inspection systems. These acoustic based technologies have
the potential to provide information in a matter of minutes to assist a utility in determining whether a
sewer pipe might be partially or fully blocked and require cleaning or renewal.
Innovative inspection approaches are now emerging that take advantage of the advances in newly
available observation and detection technologies and deployment strategies, such as acoustic- (sonic,
ultrasonic) and light- (laser, infrared) based devices that have not traditionally been applied to sewer
system investigation. These technologies are designed for rapid deployment using portable equipment
and do not necessarily require a robotic transporter in order to capture data for the entire length of the
pipe. The deployment of these non-traditional technologies, supported by emerging digital, modular,
and robotics technologies has the potential to greatly expand the "reach" of sewer system inspection
techniques, while reducing the overall cost of sewer inspections.
One commercially available line of emerging technology for the rapid assessment of gravity sewer lines
is acoustic-based technology for sewer inspection. Acoustic energy naturally follows a pipe's curvature.
ix
-------
Demonstration oj'SL-RAT™Report Executive Summary
Obstructions within the pipe will cause a portion of the acoustic energy to be reflected and absorbed. In
addition, unless the obstruction is significantly dense, a portion of the acoustic energy also passes
through. These inherent physical properties of acoustics within pipes provide the mechanisms for
evaluating a pipe's condition. Based on these mechanisms, acoustic inspection technology may be
capable of quickly evaluating the presence of blockages, features, and defects in the interior of sewer
pipes and provide informed decisions relating to the need for cleaning or further inspection using other
available technologies.
The SL-RAT is a portable, battery-operated, acoustic sewer inspection tool that provides blockage
assessment in less than 3 minutes. The SL-RAT system is composed of two basic components: 1) the
acoustic signal transmitter (TX) unit and 2) the acoustic signal receiver (RX) unit. Each SL-RAT system is
deployed as a uniquely configured "pair" of TX and RX units. The TX unit provides the active acoustic
transmission through the pipe and the RX unit provides the microphone and signal processing
capabilities to listen for and interpret the received acoustic signal. The TX and RX units are typically
deployed atop adjacent manholes on a sewer line.
Once deployed, the SL-RAT measures the dissipation of sound energy between the TX and RX units
through the airspace within the pipe (i.e., the space between the wastewater flow and the pipe wall).
Any single defect that completely obstructs the pipe will not allow the transmission of sound energy
between the TX and RX units. Additionally, aggregate obstructions within the pipe - such as roots,
grease, debris, joint offsets, hammered lateral connections, cross bores, pipe sags, high water levels etc.
- will increase the sound energy dissipation. The SL-RAT measures this "energy gap" and then develops
a blockage assessment. The overall blockage assessment by SL-RAT is provided in the form of a numeric
output value on a scale of 0 (completely obstructed) to 10 (completely unobstructed).
MSDGC is responsible for the operation and maintenance of over 3,000 miles of sewer, with
approximately 600 miles of those sewers being "off-road." These off-road sewers are typically inspected
every 8-10 years and are difficult to access, and expensive to inspect. In addition to these "off-road"
sewers, MSDGC also inspects and cleans on-road sewers on a proactive basis. For the purposes of this
study, the following three Greater Cincinnati-area locations were identified and selected for this
demonstration:
• Hunt Road - off-road sewers (see Appendix B for a detailed figure)
• Galia Drive - off-road sewers (see Appendix B for a detailed figure)
• Greenhills - on-road sewers (see Appendix B for a detailed figure)
These locations include a range of pipe sizes and a variety of pipe materials and were scheduled for
cleaning and inspection during the study year. The selected study areas have sewer pipes ranging from
6- to 12-inch diameters. The SL-RAT system deployed in this evaluation is designed to work optimally in
this pipe size range. For optimal evaluation of larger diameter pipes (i.e., greater than 18-inch diameter),
adjustments to the SL-RAT algorithm implemented in the RX unit's firmware would likely be required.
-------
Demonstration oj'SL-RAT™Report Executive Summary
A project-specific EPA required Quality Assurance Project Plan (QAPP) was developed and implemented
by the project team. Each sewer pipe-segment was to be examined and assessed using selected acoustic
methods, pole mounted camera, and CCTV prior to cleaning. If cleaning was considered necessary based
on the inspections, the sewer segments were to be cleaned, examined, and assessed again after
cleaning. Per the project's QAPP, the following strategy was specified for conducting the inspections.
Sewer line branches were to be inspected by starting at the furthest downstream pipe segment, with
the inspection regime systematically conducted to the furthest upstream pipe segment. This procedure
was specified to ensure that if any material (or debris) was dislodged during testing, the material would
flow downstream and not impact subsequent testing in the upstream pipe segments.
Besides providing a pipe condition and blockage assessment, the key advantage of implementing
technologies such as SL-RAT is the rapid deployment feature using portable equipment that can result in
significant cost savings to utilities. As mentioned previously, the Greenhills area within MSDGC was
selected to evaluate the time it takes to conduct an acoustic assessment campaign using SL-RAT. As the
goal of this study area was to evaluate the time required to perform the acoustic inspections, advanced
planning and preparation was conducted to help mitigate issues associated with traffic control and
location of manholes. This sub-study involved SL-RAT measurements at 53 pipe-segments covering
approximately 9,500 linear feet of pipe in the Greenhills study area with pipe sizes of 8" and 10"
diameters.
The emergence of acoustic sewer inspection technologies, like SL-RAT, as rapid deployment, low-cost,
reliable, pre-cleaning assessment tools is focusing growing attention on the potential for more cost-
effective sewer cleaning programs. Through the ease of deployment, reduction of cost, increases in
reliability of these inspection approaches, combined with the potential for reducing the "cleaning of
clean pipes," significant cost savings are attainable. As utilities apply these new inspection technologies,
they can move towards implementing sewer cleaning programs that consist of planned directed and
quick response, reactive cleaning. Also, these cost savings can be realized while improving collection
system performance and the protection of public health and water quality.
The results of this demonstration project reveal the potential for more cost-effective sewer cleaning
programs. The site specific pre-cleaning assessment inspection costs resulting from this project and
MSDGC's historic practices for CCTV (on-road), CCTV (off-road), and SL-RAT (on- and off-road) are
$1.68/ft., $2.03/ft., and $0.14/ft., respectively. So, for pre-cleaning assessment, the application of the
SL-RAT can reduce MSDGC's costs by $1.54/ft. for on-road sewers and $1.89/ft. for off-road sewers. In
addition, by moving to a sewer cleaning program predominated by planned directed cleaning, MSDGC
can save $2.00/ft. by reducing its "cleaning of clean pipe." In total, when costs of conventional CCTV
inspection and cleaning are combined, for each pipe segment that is deemed "clean" using the SL-RAT,
MSDGC can save $3.54/ft. for on-road sewers and $3.89/ft. for off-road sewers.
The results of this demonstration of the SL-RAT show promise for its application as a tool for cost-
effective, pre-cleaning assessment and post-cleaning quality assurance. The application of the SL-RAT in
xi
-------
Demonstration oj'SL-RAT™Report Executive Summary
an overall collection system O&M program should enable wastewater utilities to optimize their sewer
cleaning efforts and free up valuable resources to more effectively implement critical CMOM and asset
management programs.
XII
-------
Demonstration oj'SL-RAT™Report Section 1-Introduction
Section 1—INTRODUCTION
The focus on condition assessment of gravity wastewater collection systems (sewers) continues to
broaden. As sewer system networks age, the risk of deterioration, blockages, and collapses becomes
increasingly of concern. The consequences of these events and conditions can negatively impact a
community's social, environmental and financial well-being. As a result, sewer system owners and
operators worldwide are taking proactive measures to better maintain and improve the performance
levels of their sewer systems. Sewer system owners and operators are progressively addressing
operational issues prior to their occurrence, when possible, and obtaining information concerning the
condition of their sewer system assets.
Traditionally, the main focus of condition assessment of sewers has been directed at operational issues
related to the collection and conveyance of flows to a facility for treatment and disposal. To address
operational issues, attention has tended to concentrate on maintenance activities associated with the
cleaning and removal of debris and foreign materials from collection system pipes. The presence of
debris and foreign material in sewer pipes reduces capacity and inhibits sewage from flowing through
the system to the treatment facilities as intended. Additionally, attention has been directed towards the
reduction of excessive hydraulic loading of sewers due to wet-weather induced infiltration and inflow
(l&l) entering and over burdening the hydraulic capacity of the sewers and wastewater treatment
plants. The combination of debris and extraneous wet-weather induced flows can result in less than
desired levels of customer service and possibly cause raw sewage to overflow from the collection
system or to result in basement backups. Unintended overflows from a wastewater collection system
are commonly referred to as sanitary sewer overflows (SSOs).
Occasional unintentional discharges of raw sewage (i.e., SSOs) from municipal sanitary sewers occur in
almost every system. SSOs result from a variety of causes, including but not limited to line blockages,
line breaks, and sewer defects that allow storm water and groundwater to overload the system; lapses
in sewer system operation and maintenance; power failures; inadequate sewer design; and vandalism.
The U.S. Environmental Protection Agency (EPA) estimates that there are at least 23,000 - 75,000 SSOs
per year (not including the sewage backups into buildings). The untreated sewage from these overflows
can contaminate the nation's water resources, causing serious water quality problems. Sewage can also
backup into basements, causing property damage and threatening public health (EPA, 2012).
1.1 Maintenance of Sanitary Sewers
Many avoidable SSOs are caused by inadequate operation or maintenance, inadequate system capacity,
and improper system design and construction. These SSOs can be reduced or eliminated by the
following practices (EPA, 2012):
1-1
-------
Demonstration oj'SL-RAT™Report Section 1-Introduction
• Sewer system cleaning and maintenance
• Reducing l&l through system rehabilitation and repairing broken or leaking service lines.
• Increasing or upgrading sewer, pump station, or sewage treatment plant capacity and reliability.
• Construction of wet-weather storage and high-rate treatment facilities to treat excess flows.
Cleaning and inspecting sewer pipes is essential for utilities to operate and maintain a properly
functioning system and minimize SSOs; these activities further a community's reinvestment in its
wastewater infrastructure (EPA, 1999). For many utilities, sewer cleaning and inspection programs are
generally part of larger umbrella programs. These programs are commonly referred to by the utilities
and regulatory agencies as capacity, management, operation and maintenance (CMOM) and asset
management programs. Effective operation and maintenance (O&M) of a collection system is an
essential element of any CMOM and asset management program (EPA, 2005).
The routine maintenance of a sewer system often includes sewer system cleaning, root
removal/treatment, and cleaning/clearing of sewer mainline blockages. However, understanding where
and when to perform cleaning activities in the most effective manner is not necessarily a straight
forward task. Some agencies clean their sewer system as a matter of course without knowing in advance
whether the system or portions of the system require cleaning. Pipes with blockages receive the same
attention and resources as those with no actual cleaning needs. The use of staff and equipment is not
optimized in this approach and staff time and resources that could be directed to other more productive
O&M activities are lost.
In an attempt to direct maintenance staff and cleaning equipment to those pipes in a sewer system that
require attention, some agencies identify cleaning needs by conducting inspection of the sewers prior to
cleaning. These pre-cleaning inspections are conducted using various approaches and equipment to
varying degrees of success, efficiency and speed.
The speed and cost associated with traditional methods for pre-cleaning inspections vary greatly. The
rapid assessment of sewers to determine the need for cleaning and to possibly identify defects is an
approach that is capturing wide attention of many wastewater utilities. Rapid assessment approaches
and tools provide an avenue to significant pre-cleaning inspection cost savings that could be achieved
through reduced inspection and non-productive cleaning costs.
The overall objective of this EPA funded study was to demonstrate a recently developed innovative
acoustic-based sewer line assessment technology that is designed for rapid deployment using portable
equipment. This technology can provide a rapid assessment of the need for pipe cleaning and an overall
pipe-condition assessment. Acoustic technologies require a minimal amount of equipment when
compared to closed-circuit television (CCTV) inspection systems. These acoustic based technologies have
the potential to provide information in a matter of minutes to assist a utility in determining whether a
sewer pipe might be partially or fully blocked and require cleaning or renewal. The speed of the
assessment, using minimal equipment, has the potential to result in significant cost-savings compared to
traditional methods, such as CCTV inspection. It is generally known that smaller diameter pipes (i.e., less
than or equal to 12-inch diameter) contribute to over 90 percent of the sewer main backups reported in
1-2
-------
Demonstration oj'SL-RAT™Report Section 1-Introduction
a typical city (Sprague, J., 2007). This study hence focused on the demonstration of a acoustic
technology that is suited for smaller diameter pipes.
1.2 Sewer Line Inspection Techniques
The traditional sewer system inspection methodologies used for pre-cleaning assessment and
inspection-based condition assessment are generally based on visual observations. Most inspections of
sewer lines are performed primarily by one or more of the following established inspection techniques:
• Visual (historical)
• Lamping (historical)
• Pole/Stick Mounted Zooming Cameras
• CCTV
• Laser profiling
• Sonar assessment
The historical approaches to visually examining sewers have been used to varying degrees of success. In
the past, before camera and robotic equipment were widely available, workers often entered a
maintenance access point (manhole) and visually examined the pipes. This method of pipeline
inspection is rarely used today due to worker safety considerations, limitations inherent to the
inspection method, and the introduction of technologies that allow for remote, non-entry, camera-
based inspections.
Workers have long used light sources lowered into sewer access structures or manholes in an attempt at
illuminating the interior of a pipe. A second worker positioned at grade at an adjacent manhole then
attempts to see if the light has reached the adjacent manhole. If light is observed, the pipe is assumed to
be relatively free of obstructions. If light is not observed, the pipe is assumed to have a blockage that
also obstructs flow. The pipe would then typically be cleaned in an attempt to remove the blockage.
Inspection of a pipe in this manner has been referred to as lamping of lines or simply lamping. Many
older sewer systems have lamp holes constructed in the sewers to facilitate this type of inspection. The
fundamental issue with lamping of lines is that the entire inspection relies on whether light can visibly
be seen from one access structure to the next. The inspectors cannot directly see whether a sewer pipe
requires cleaning or if a structural defect exists. Such structural defects might include conditions such as
misalignment of the pipeline, sags, protruding taps or a collapsed pipe. A variation of line lamping that
has been used extensively is for a worker to enter a manhole and shine a bright light and view the pipe
condition using a mirror or direct observation. The approach can be effective but only a small
percentage of the line can be inspected.
More recently, cameras have been mounted on poles, much like a painter's extension pole commonly
referred to as cameras on a stick or pole-mounted cameras. A pole-mounted camera is lowered into the
manhole by an operator standing at street level, and the camera operator directs the camera's view into
the pipes connected to the manhole. On an integrated monitor, the equipment operator remotely views
at street level what the camera observes in the pipe. These cameras are now commonly equipped with
1-3
-------
Demonstration oj'SL-RAT™Report
Section 1-Introduction
operator controlled lighting and camera focus/zooming capabilities to augment the inspection in an
attempt to view and inspect the entire pipe length between access structures.
Pole-mounted zooming cameras have been a significant advancement over lamping of lines. However,
issues with lighting the entire length of the pipe between access structures and the ability to focus the
camera lens at significant distances in poor lighting conditions limit the usefulness of these tools.
Furthermore, if the pipe is misaligned and not straight, water vapor is present, or obstructions such as
roots or other matter are present, the effectiveness of this tool is further diminished and limited.
Robotic platforms, mounted with camera-based technologies, have been in use for sewer inspections for
more than 50 years. These robotic systems allow for CCTV camera equipment to be remotely operated,
controlled, and monitored from ground level. The inspection images can be viewed immediately and
transferred to data storage devices for viewing and evaluation at a later time. Advances in technology
include self-propelled equipment, digital imaging and 360-degree field of view. The cameras are
transported into the length of sewer pipes for direct visual inspection via the camera. These CCTV
systems are now widely used and, over the course of the past 20 to 30 years, become the current
industry standard for direct visual inspection of sewer pipes. A majority of utilities own and operate
CCTV systems or have contract(s) for the provision of CCTV services.
The most common type of robotic CCTV inspection systems in use for inspection of public sewers
requires vans, trucks, or similar vehicles for their operation. If sewers are located off-road, all wheel
drive or four wheel drive vehicles may be required to access the manhole structures. A new vehicle
equipped with a CCTV inspection system will typically cost between $100,000 and $200,000, and require
a minimum crew of two persons. Custom off-road vehicles equipped with CCTV systems are even more
expensive to own and operate. Figure 1-1 shows a custom off-road CCTV camera tractor owned and
operated by the Metropolitan Sewer District of Greater Cincinnati (MSDGC).
Figure 1-1. Custom Off-road CCTV Camera Tractor (Courtesy: MSDGC).
1-4
-------
Demonstration oj'SL-RAT™Report Section 1-Introduction
The use of laser and sonar profiling technologies for the inspection and condition assessment of sewers
has been introduced in recent years (EPA, 2009). Laser profiling technology is increasingly being used to
inspect sewers. Laser profiling goes beyond visual inspection and allows for geometric measurements to
be obtained. However, the adoption of laser profiling for pre-cleaning inspection is of limited added
value beyond what CCTV can provide.
Unlike CCTV and laser technologies, sonar profiling equipment requires that the sensing apparatus be
completely submerged and only provides an assessment of the pipe condition under the water level.
Therefore, the equipment is often coupled with CCTV equipment so that the pipe above and below the
water level can be inspected. Sonar assessment is useful in locating and mapping debris especially in
large diameter pipes with significant base-flow, water filled siphons and pressurized force mains.
1.3 Industry Standard Sewer Inspection Methodology
The National Association of Sewer Service Contractors (NASSCO) has established "de-facto" industry
standards for the use of CCTV systems in sewers. The standards include acceptable operating
parameters as well as observation and defect coding standards for sewer inspection. NASSCO offers the
Pipeline Assessment and Certification Program (PACP) for CCTV operators and those who analyze and
interpret CCTV data. The NASSCO PACP system provides for the standardization of the description of
defects within the industry.
Inspections performed in compliance with the NASSCO PACP require that CCTV inspections be
conducted at a pace of no more than 30 feet per minute for camera transporter travel. PACP compliant
inspections also require that the system operator stop and view observed pipe defects and features.
Advanced technologies using high-definition (HD) digital scanning and imaging CCTV systems are capable
of traveling at a faster pace without the need to stop and view observed pipe defects and features,
while maintaining visual clarity and gaining high resolution, enhanced defect, and feature observation.
The capture of data from these scanning systems allows for virtual pan, tilt zoom operations and post-
inspection coding of defects and features. Use of these scanning systems is acceptable under the
NASSCO PACP system if image quality is adequate and meets minimum PACP standards.
Typical average daily CCTV inspection production rates vary from operator-to-operator and from site-to-
site. A multitude of factors affect the typical average daily production rates. Such factors include the
availability of system access (most commonly manholes) locations, distance between access locations,
pipe diameter, pipe materials, flow depth and velocity in the pipes, presence of debris, number of
defects, number of features, CCTV system cable length, transporter weight, and other factors. An
average daily production rate between 1,000 feet to 4,000 feet can be expected.
CCTV has revolutionized how sewer systems are operated, maintained, and inspected, and made sewer
pipe inspection relatively safe when compared to previous methods of inspection. It is an invaluable tool
for sewer inspection. Its greatest strength is its ability to visually examine and inspect the entire length
of a pipe. This strength imposes CCTV inspection's greatest limitation - the CCTV system must travel the
entire length of a pipe to complete an inspection. Significant blockages, defects, or lack of available
access denies its ability to inspect the sewer in part or total.
1-5
-------
Demonstration oj'SL-RAT™Report Section 1-Introduction
1.4 Innovative Sewer Inspection Methodologies
Multi-sensor robotic transporter platforms have been developed and introduced to the industry that
allow for the coupling of laser and sonar profiling technologies onto a remotely operated and controlled
CCTV inspection system. These systems provide for significant advancements in the ability to inspect a
sewer system. These technologies are typically integrated with the CCTV camera transporter, increasing
the overall cost, but providing additional insights into the condition of the sewer.
Innovative inspection approaches are now emerging that take advantage of the advances in newly
available observation and detection technologies and deployment strategies, such as acoustic- (sonic,
ultrasonic) and light- (laser, infrared) based devices that have not traditionally been applied to sewer
system investigation. These technologies are designed for rapid deployment using portable equipment
and do not necessarily require a robotic transporter in order to capture data for the entire length of the
pipe. The deployment of these non-traditional technologies, supported by emerging digital, modular,
and robotics technologies has the potential to greatly expand the "reach" of sewer system inspection
techniques, while reducing the overall cost of sewer inspections.
One commercially available line of emerging technology for the rapid assessment of gravity sewer lines
is acoustic-based technology for sewer inspection. This technology provides for the acoustic "lamping"
of lines rather than using a light source to illuminate the lines. Acoustics has an inherent advantage over
light for inspecting the interior of sewer pipes. Light energy tends to disperse within a sewer pipe. If an
obstruction is encountered, the light energy is scattered (including back towards the light source). This
allows the obstruction to be seen or videoed. Obstructions include water vapor, the pipe wall and pipe
curvatures. Acoustic energy naturally follows a pipe's curvature. Obstructions within the pipe will cause
a portion of the acoustic energy to be reflected and absorbed. In addition, unless the obstruction is
significantly dense, a portion of the acoustic energy also passes through. These inherent physical
properties of acoustics within pipes provide the mechanisms for evaluating a pipe's condition. Based on
these mechanisms, acoustic inspection technology may be capable of quickly evaluating the presence of
blockages, features, and defects in the interior of sewer pipes and provide informed decisions relating to
the need for cleaning or further inspection using other available technologies.
CCTV sewer inspections, especially in "off road" conditions, generally require special equipment, such as
a highly customized vehicle equipped with an on-site generator, remotely operated transporter, tether
cable and spool system, operator control hardware, a computer system, specialized software, and
various other tools. Acoustic sewer inspections require much less supporting equipment and the
inspection equipment is portable, allowing for easier access to remote sites.
Sewer inspections with acoustic-based technology have the potential of being performed in a fraction of
the time in which CCTV inspections are performed; increasing the rate of productivity of the inspections
and reducing the cost of the inspections.
A portable acoustic inspection system can assist in making a quick diagnostic determination whether a
sewer line needs to be cleaned or if it needs to be investigated further using CCTV inspection. These
diagnostic determinations will allow the utility to more cost-effectively deploy their limited resources to
1-6
-------
Demonstration oj'SL-RAT™Report Section 1-Introduction
areas that require cleaning or further investigation. It will optimize the deployment of the special
equipment and crews required for CCTV inspection to where they are most needed, thus increasing the
cost-effectiveness of their CCTV inspection program.
1.5 Study Objective
The overall objective of this EPA-funded study was to demonstrate innovative sewer line assessment
technologies that are designed for rapid deployment using portable equipment. This study focused on
demonstration of technologies that are suitable for smaller diameter pipes (less than 12-inch diameter).
One recently developed and commercially-available acoustic-based sewer pipe assessment technology is
the Sewer Line- Rapid Assessment Tool (SL-RAT™) manufactured by InfoSense, Inc. (InfoSense) of North
Carolina. This report summarizes the collaborative demonstration and evaluation of the SL-RAT.
1.6 SL-RAT Equipment Overview
The SL-RAT is a portable, battery-operated, acoustic sewer inspection tool that provides blockage
assessment in less than 3 minutes. The SL-RAT system is composed of two basic components: 1) the
acoustic signal transmitter (TX) unit and 2) the acoustic signal receiver (RX) unit. Each SL-RAT system is
deployed as a uniquely configured "pair" of TX and RX units. The TX unit provides the active acoustic
transmission through the pipe and the RX unit provides the microphone and signal processing
capabilities to listen for and interpret the received acoustic signal. The TX and RX units are typically
deployed atop adjacent manholes on a sewer line. Figure 1-2 shows the SL-RAT's conceptual
deployment for blockage assessment.
Transmitter Ł* SL-RAT .*., Receiver
Sewer Line Rapid
Assessment Tool
Figure 1-2. SL-RAT Conceptual Deployment.
Deploying the SL-RAT involves transporting the TX and RX units to the sewer access points (manholes).
At the manholes, when the units are turned on, the onboard firmware conducts an initialization process
and in less than five minutes the units are ready to operate. The TX/RX units should remain turned on
when moving from one location to another throughout the work day. This eliminates the initialization
1-7
-------
Demonstration oj'SL-RAT™Report
Section 1-Introduction
time and allows the units to be ready for operation. Figure l-3(a) shows the SL-RAT units in their
transport mode at one of the EPA study sites. To perform an acoustic inspection with the SL-RAT, the
manhole covers at both ends of a pipe section are either partially or fully removed. The SL-RAT units are
then placed in their operational mode as depicted in Figure l-3(b) and (c) for the RX and TX units,
respectively. For off-road or on-road inspections, the SL-RAT can be easily transported manually with the
RX unit weighing 11 pounds and the TX unit weighing 18 pounds. Typical usage involves inspecting
multiple pipe segments along a leg of a sewer line. This is facilitated by only moving one unit at a time
after each inspection (effectively "leap frogging" the units down the sewer line). Tests are conducted
while the pipe is in operation, with no need to restrict or change the flow conditions. The units can be
deployed for testing in either the upstream or downstream direction.
Figure 1-3. SL-RAT Deployment at EPA Project Site: (a) TX and RX Units in Transport Mode, (b) RX Unit
Operational Mode Deployment, (c) TX Unit Operational Mode Deployment.
1-8
-------
Demonstration oj'SL-RAT™Report Section 1-Introduction
Once deployed, the SL-RAT measures the dissipation of sound energy between the TX and RX units
through the airspace within the pipe (i.e., the space between the wastewater flow and the pipe wall).
Any single defect that completely obstructs the pipe will not allow the transmission of sound energy
between the TX and RX units. Additionally, aggregate obstructions within the pipe - such as roots,
grease, debris, joint offsets, hammered lateral connections, cross bores, pipe sags, high water levels etc.
- will increase the sound energy dissipation. The SL-RAT measures this "energy gap" and then develops
a blockage assessment. The assessment uses a proprietary algorithm based on a statistical model of
sound behavior in conduits that was developed through several years of empirical research on sewage
lines. The only operator input required to perform an inspection is the approximate length, in 50 foot
increments, of the pipe segment between the TX and RX units. This estimate may be aided by the RX and
TX themselves as they are able to suggest an estimated pipe-length based on Global Positioning System
(GPS) and radio frequency communication in the majority of cases. The overall blockage assessment by
SL-RAT is provided in the form of a numeric output value on a scale of 0 (completely obstructed) to 10
(completely unobstructed). Table 1-1 summarizes the relative output value provided by SL-RAT in
comparison to an expected visual assessment based on CCTV. Charlotte Mecklenburg Utilities (CMU) has
tested this technology during the development phase and has developed action plans based on the
output results (Fishburne, J. 2011). For example, if the SL-RAT output results are in the 7 tolO range, the
pipe is considered to be clear, if the results were 0 to 4, the pipe is in need of cleaning or further
investigation to determine the cause of the poor SL-RAT results. Additionally, depending on the available
resources, any other score in the mid-range may undergo additional investigation to further determine if
cleaning is needed.
Table 1-1. Comparative SL-RAT vs. CCTV Blockage Assessment.
10 No significant obstructions within the pipe
Minor impediments within the pipe such as joint offsets, partial sags,
7'9 protruding laterals, debris, minor grease, and/or minor root fibers.
Impediments within the pipe such as joint offsets, partial sags,
4.5 protruding laterals, debris, grease, and/or root fibers. Single or
multiple occurrences.
Significant impediments within the pipe such as multiple joint offsets,
near full pipe sag, multiple protruding laterals, significant debris,
1~3 significant grease, significant root fibers and/or root balls. Single or
multiple occurrences.
Full pipe sag; single or multiple obstructions within the pipe reaching
or nearly reaching the flow.
Since the SL-RAT employs sound energy to detect blockages, it can negotiate bends and obstacles -
unlike a pole-mounted zooming camera that relies on straight visual sight lines. InfoSense's prior
deployments of SL-RAT have indicated that, with sufficiently low ambient noise levels, users have
1-9
-------
Demonstration oj'SL-RAT™Report Section 1-Introduction
reliably obtained measurements for up to 800 foot pipe-distances between the TX and RX modules. For
the greatest reliability, it is recommended that the SL-RAT inspections be conducted between adjacent
manholes. The results of the assessment are immediately displayed to the user at the time of testing.
The SL-RAT device is also equipped with a GPS chip for location determination, as well as other
electronics that allow the paired TX and RX units to communicate via radio frequencies (RF). Additional
data, such as time stamp, user identification, and GPS location, are stored in an encrypted format on the
device that can be uploaded for archiving and further analysis to InfoSense's cloud-based Sewer Line
Diagnostic OrGanizer (SL-DOG) via a Universal Serial Bus (USB) connection to a personal computer (PC).
The SL-DOG provides post-processing, allowing the infield blockage assessment to be verified and assist
in location registration of the blockage assessment as well as correcting the acoustic assessment result
for operator errors in estimating the pipe length. These features are further discussed in Appendix A -
SL-DOG Condition Assessment Data Verification.
1.7 Project Team
This collaborative field demonstration of the SL-RAT was led by EPA's National Risk Management
Research Laboratory (NRMRL) in Cincinnati, Ohio. EPA engaged MSDGC as a collaborative research
partner to provide access to the study area (see Section 2.0) sewer lines and to perform the related field
work. For coordinating and performing this demonstration, EPA issued a work assignment to Pegasus
Technical Services, Inc. (PTSI) under EPA Contract No: EP-C-11-006. Shaw Environmental &
Infrastructure, Inc. (Shaw - a team subcontractor to PTSI) served as the project lead to assist in the
selection of technology vendors, obtain the equipment through lease, coordinate the field efforts with
MSDGC, evaluate the data generated, and produce this report with the project team.
To perform these tasks, Shaw subcontracted with Brown and Caldwell (BC) and ALSA Tech LLC (ALSA) to
serve as industry experts/consultants in this demonstration. In addition, Shaw contacted selected
technology vendors (e.g., InfoSense) to arrange for the lease of the SL-RAT device. The members of this
project team included:
• EPA - Dan Murray, Patrick Clark and John Olszewski
• MSDGC - Jerry Weimer, Eric Withers, Eric Schneider, Dustin Prue, and Mike Pittinger
• Shaw - Srinivas Panguluri and Don Schupp
• BC-Gary Skipper and Steve Donovan
• ALSA - Abraham Chen
• InfoSense - Ivan Howitt and Alex Churchill
The EPA and Shaw project team participated in this collaborative field demonstration mainly as neutral
observers during the field activity-phase of this study. The project team's main objective was to compile
the data collected by MSDGC and perform the evaluation contained in this report. The project team
members periodically accompanied MSDGC personnel while they deployed the equipment and assessed
the condition of sewers in the Cincinnati area using both a conventional CCTV camera-based inspection
system and the SL-RAT. Specifically, the results obtained from the following technologies will be
discussed in this report:
1-10
-------
Demonstration oj'SL-RAT™Report Section 1-Introduction
• SL-RAT manufactured by InfoSense, Inc.
• Pan-Tilt-Zooming pole-mounted camera (aka "camera on a stick") manufactured by Envirosight
Quickview.
• HD-digital scanning CCTV or the PANORAMO 3D Optical Pipeline Scanner manufactured by
RapidView-IBAK.
1-11
-------
Demonstration oj'SL-RAT™Report
Section 2-Study Area Description & Eval. Parameters
Section 2—STUDY AREA DESCRIPTION AND
EVALUATION PARAMETERS
MSDGC is responsible for the operation and maintenance of over 3,000 miles of sewer, with
approximately 600 miles of those sewers being "off-road." These off-road sewers are typically inspected
every 8-10 years and are difficult to access, and expensive to inspect. In addition to these "off-road"
sewers, MSDGC also inspects and cleans on-road sewers on a proactive basis. For the purposes of this
study, the following three Greater Cincinnati-area locations were identified and selected for this
demonstration:
• Hunt Road - off-road sewers (see Appendix B for a detailed figure)
• Galia Drive - off-road sewers (see Appendix B for a detailed figure)
• Greenhills - on-road sewers (see Appendix B for a detailed figure)
These locations include a range of pipe sizes and a variety of pipe materials and were scheduled for
cleaning and inspection during the study year. Tables 2-1 and 2-2 summarize the total number of pipe
segments by size and material type selected for this study.
Table 2-1. Hunt Road, Galia Drive, and
Greenhills Pipe Segment Size Summary.
Table 2-2. Hunt Road, Galia Drive, and Greenhills Pipe
Segment Material Summary.
Pipe Size (in) No. of Segments
6
8
10
12
Total
1
97
1
56
155
Pipe Materia1
Concrete (RCP)
Ductile Iron Pipe (DIP)
Cast Iron Pipe (CIP)
Vitrified Clay Pipe (VCP)
Poly-Vinyl Chloride (PVC)
Slip-lined
Unknown
No. of Segments
75
60
11
As summarized in Table 2-1, the selected study areas have sewer pipes ranging from 6- to 12-inch
diameters. The SL-RAT system deployed in this evaluation is designed to work optimally in this pipe
size range. For optimal evaluation of larger diameter pipes (i.e., greater than 18-inch diameter),
adjustments to the SL-RAT algorithm implemented in the RX unit's firmware would likely be required.
2.1 Test Conditions
A project-specific EPA required Quality Assurance Project Plan (QAPP) was developed and implemented
by the project team (EPA, 2012b). As part of the QAPP, the inspections were to be conducted during
times when the water level in the sewer was below 40 percent of pipe diameter and there were no
significant changes to the water levels between the technology deployments. Each sewer pipe-segment
2-1
-------
Demonstration oj'SL-RAT™Report Section 2-Study Area Description & Eval. Parameters
was to be examined and assessed using selected acoustic methods, pole mounted camera, and CCTV
prior to cleaning. If cleaning was considered necessary based on the inspections, the sewer segments
were to be cleaned, examined, and assessed again after cleaning. Figure 2-1 depicts the overall test
procedure that MSDGC was to follow during this study. Figure 2-2 shows the inspection test procedure,
and Figure 2-3 shows the mainline CCTV test procedure. As indicated in Figure 2-1, another acoustic
inspection technology - SewerBatt was also evaluated during this demonstration study with results
contained in a separate EPA report. Both acoustic inspection technologies were evaluated using the
same underlying CCTV-based PACP assessments.
2.2 Condition Assessment/Inspection Strategy
Per the project's QAPP, the following strategy was specified for conducting the inspections. Sewer line
branches were to be inspected by starting at the furthest downstream pipe segment, with the
inspection regime systematically conducted to the furthest upstream pipe segment. This procedure was
specified to ensure that if any material (or debris) was dislodged during testing, the material would flow
downstream and not impact subsequent testing in the upstream pipe segments.
For each pipe segment, the following inspection regime was employed for the specified technologies
and in the specified sequence:
• SL-RAT
• Pole/Stick Mounted Camera
• CCTV and/or PANORAMO Pipeline Scanner
The inspection sequence for the technologies was selected so that the pipe segment's condition would
remain consistent over the inspections by each technology. For example, since the SL-RAT does not
come in contact with the flow, performing this inspection first does not impact the condition of the pipe
segment for the subsequent camera-based inspections.
In January 2013, at the outset of the field demonstration, the SL-RAT representatives from InfoSense
visited Cincinnati to train all project personnel on the appropriate techniques to deploy and use the SL-
RAT equipment. After the initial training session, the vendor remained onsite for a day as an observer to
verify correct SL-RAT operation by the MSDGC operators and to address any questions. Due to
scheduling issues, the SL-DOG software was installed at the MSDGC facility several weeks later, based on
communication via telephone conference between MSDGC and InfoSense personnel. Thereafter,
InfoSense personnel were available, if required, for further consultation by MSGDC personnel via email,
teleconference, or by onsite visit. However, no additional contact with the vendor was required by
MSDGC during the remaining course of the project. Per the QAPP, Shaw, BC, and EPA personnel
accompanied the MSDGC crew periodically to observe the inspection and the data collection process.
2-2
-------
Demonstration oj'SL-RAT™Report
Section 2-Study Area Description & Eval. Parameters
EPA TEST PROCEDURE OVERALL
Figure 2-1. Overall Test Procedure.
2-3
-------
Demonstration oj'SL-RAT™Report
Section 2-Study Area Description & Eval. Parameters
EPA TEST PROCEDURE INSPECTION
FIELD
SUPERVISOR
EQUIPMENT
SPECIALIST
EQUIPMENT
SPECIALIST
Figure 2-2. Inspection Test Procedure.
2-4
-------
Demonstration oj'SL-RAT™Report
Section 2-Study Area Description & Eval. Parameters
EQUIPMENT
SPECIALIST
EQUIPMENT
SPECIALIST
Figure 2-3. CCTV Test Procedure.
2-5
-------
Demonstration oj'SL-RAT™Report Section 2-Study Area Description & Eval. Parameters
2.3 CCTV and Pole Mounted Zooming Camera Data Evaluation Procedure
As indicated in the previous sections, two camera-based technologies where specified in the QAPP to be
used as part of the inspection regime for each pipe segment evaluated. The two specific camera
technologies used during the project were:
• Envirosight Quickview (Pole/Stick Mounted Camera) -handheld pole mounted zooming camera
used to visually inspect and assess the sewer condition.
• PANORAMO - robotic CCTV which utilizes two high-resolution 186° wide-angle camera lenses to
capture a complete 360° spherical image of the pipe. The video recording images can be
unfolded and assessed in real time or at a later date. The system permits computer-aided
measurement of the positions and sizes of objects or pipe defects.
For both camera-based technologies, the condition assessment of the sewer segments was based on the
NASSCO PACP methodology. The PACP provides a standard method for coding each defect, based on a
visual assessment of the type and extent of the observed defect within a pipe segment. The PACP
methodology stipulates a mapping between defect codes to a numeric pipe condition grade. The general
assignment of pipe condition grades are:
• Grade 5 - Pipe segment has failed or will likely fail within the next five years. Pipe segment
requires immediate attention.
• Grade 4 - Pipe segment has severe defects with the risk of failure within the next five to ten
years. Pipe condition is generally poor and will likely become Grade 5 in near future.
• Grade 3 - Pipe segment has moderate defects and the condition is fair to moderate.
Deterioration may continue, but not for ten to twenty years.
• Grade 2 - Pipe segment has minor defect, but generally good and has not begun to deteriorate.
Pipe is unlikely to fail for at least 20 years.
• Grade 1 - Pipe segment may have minor defects, but otherwise in excellent condition. Failure is
unlikely in the foreseeable future.
Using the set of pipe condition grades determined by a pipe segment's defect codes, the pipe segment's
condition rating can be evaluated. The condition rating is a single numeric value representing the
relative condition assessment for the pipe segment. The NASSCO PACP provides several methods for
evaluating the condition rating for a pipe segment. One approach for aggregating the pipe condition
grades (as specified by the PACP) is given by a weighted sum of the number of pipe condition grades
occurrences where the weighting factor is the Grade number, i.e., Rating = Ef=i i x ^i
where Nt is the number of occurrences of the ith Grade. An alternative approach specified by the PACP
for aggregation is a weighted average:
Rating
Index = .
2-6
-------
Demonstration oj 'SL-RAT™ Report Section 2-Study Area Description & Eval. Parameters
To illustrate, given a pipe segment's PACP evaluation results in the following condition grading: eleven
Grade 1 defects, one Grade 2 defect, three Grade 3 defects and one Grade 5 defect, then
Rating = (1 x 11) + (2 x 1) + (3 x 3) + (5 x 1) = 27
IndeX= 7 =1'69
The PACP condition Rating and condition Index will be presented along with the blockage assessment
score from the SL-RAT as outlined in Section 1.6.
2.4 Rapid Deployment Evaluation Procedure
Besides providing a pipe condition and blockage assessment, the key advantage of implementing
technologies such as SL-RAT is the rapid deployment feature using portable equipment that can result in
significant cost savings to utilities. As mentioned previously, the Greenhills area within MSDGC was
selected to evaluate the time it takes to conduct an acoustic assessment campaign using SL-RAT. As the
goal of this study area was to evaluate the time required to perform the acoustic inspections, advanced
planning and preparation was conducted to help mitigate issues associated with traffic control and
location of manholes. All manholes were pre-marked, and motorized All Terrain Vehicles (ATVs) were
used to conduct this campaign. This sub-study involved SL-RAT measurements at 53 pipe-segments
covering approximately 9,500 linear feet of pipe in the Greenhills study area with pipe sizes of 8" and
10" diameters. It should be noted that the NASSCO-PACP CCTV assessments were performed only for
four of the 53 pipe-segments in the Greenhills study area.
2-7
-------
Demonstration ofSL-RAT™Report Section ^-Technology Demonstration Results
Section 3—TECHNOLOGY DEMONSTRATION RESULTS
The inspection test procedure shown previously in Figure 2-2 and the CCTV test procedure depicted in
Figure 2-3 were not accomplished for every pipe segment during the course of the project. This was due
to a variety of reasons including access limitations, wet-weather rain events that interrupted the
schedule, unscheduled CCTV tractor repairs, and the unforeseen periodic need for the MSDGC crew to
address issues requiring immediate attention. The change in procedure was not due to the SL-RAT
operation or its failure to operate as specified by the vendor. Due to the impact on the test procedure,
the data/results presented in the following sections are the field findings based on the time frame
during which they were collected. As indicated in Section 2, video data were collected using both the
pole/stick mounted camera and the CCTV camera. In assessing the two sets of video data collected, the
data obtained from the pole/stick mounted camera provided limited to no additional benefit for
achieving the goals outlined in the QAPP (i.e., demonstrating/evaluating the acoustic inspection
technology condition assessment performance based on the SL-RAT), and therefore has not been
included in this document.
To facilitate the SL-RAT evaluation in the following sections, the SL-RAT assessment was divided into
three categories: Upper Range (7-10), Medium-Range (4-6), and Low Range (0-3). This categorization is
consistent with the vendor's categories (see Table 1-1): Good (7-10), Fair (4-6), Poor (1-3) and Blocked
(0). A similar classification is used by CMU (Fishburne, J. 2011): Maintenance Action Not Required (7-
10), Maintenance Action Required (0-4).
3.1 Galia Drive Study Area CCTV/SL-RAT Assessment Summary
The Galia Drive evaluation area consists mainly of off-road sewers, through a wooded area serving
several residential subdivisions. The terrain has very high slopes and access to the manholes is provided
by an unpaved path cut through the area. The alignment of the sewer along the path is above a steep
ravine that leads to an unnamed creek in the Muddy Creek watershed. The initial training on the SL-RAT
operation and the inspections began in January 2013. All of the inspections listed in this section were
performed between January 2013 and May 2013.
Of the fifty-four (54) sewer pipe-segments originally identified for inclusion in the Galia study area, only
a total of thirty-four (34) individual pipe-segments were inspected through either PANORAMO or CCTV,
or both. Many pipe-segments were inspected more than once due to several weeks of equipment
breakdown and weather-related site access issues. No issues were encountered with the operation of
the SL-RAT.
During the same period, a total of sixty-three (63) valid SL-RAT assessment tests were recorded in this
study area. These sixty-three (63) SL-RAT assessments represent thirty-seven (37) sewer pipe-segments;
again, many segments were assessed more than once due to interruptions and field crew re-deployment
in the spring. Nine (9) of the sixty-three (63) SL-RAT assessments did not have any CCTV inspection data
3-1
-------
Demonstration oj'SL-RAT™Report
Section ^-Technology Demonstration Results
for comparison purposes. Therefore, fifty-four (54) SL-RAT assessments are supported by CCTV
inspection data. Table 3-1 summarizes the SL-RAT test results and associated CCTV inspection findings
for the Galia Drive study area.
Table 3-1. Summary of SL-RAT and CCTV Results Galia Drive.
H^^af^^l
619
672
624
699
700
615
701
609
702
610
703
613
704
614
705
646
706
622
^ffi
11702001-
11702002
11702001-
11702002
11702003-
11702012
11705009-
11706007
11705009-
11706007
11705010-
11705009
11705010-
11705009
11705011-
11705010
11705011-
11705010
11705012-
11705011
11705012-
11705011
11705013-
11705012
11705013-
11705012
11705014-
11705013
11705014-
11705013
11705015-
11705014
11705015-
11705014
11706002-
11707005
1/28/2013
11:17
4/16/2013
11:16
1/29/2013
14:24
4/18/2013
9:34
4/18/2013
9:39
1/25/2013
15:29
4/18/2013
9:45
1/24/2013
14:02
4/18/2013
9:56
1/24/2013
14:13
4/18/2013
10:18
1/25/2013
11:52
4/18/2013
10:24
1/25/2013
11:59
4/18/2013
10:36
3/20/2013
10:26
4/18/2013
10:42
1/28/2013
12:34
Iffl^ft^l
^ffi
150
150
150
150
150
150
150
350
350
250
250
250
250
150
150
250
150
250
91
166
142
234
234
67
151
214
276
231
290
204
279
230
117
107
127
262
9
9
8
9
9
9
10
10
9
9
10
9
8
9
8
9
9
8
Good
Good
Good
Good
Good
Good
Good
Good
Good
Good
Good
Good
Good
Good
Good
Good
Good
Good
xxxxxx
4/30/2013
1/29/2013
3/18/2013
5/2/2013
xxxxxx
5/2/2013
xxxxxx
5/2/2013
xxxxxx
5/2/2013
xxxxxx
5/3/2013
xxxxxx
5/3/2013
xxxxxx
5/3/2013
xxxxxx
^ffl ffia
xxxxxxx
Light
grease
No issues
No Issues
No issues
xxxxxxx
Fine roots
xxxxxxx
Fine roots
xxxxxxx
Slight
debris
xxxxxxx
Roots Med
xxxxxxx
No issues
xxxxxxx
Roots fine
xxxxxxx
3-2
-------
Demonstration oj'SL-RAT™Report
Section ^-Technology Demonstration Results
^^9
674
710
626
675
708
627
676
677
628
629
678
620
621
673
630
679
680
631
632
681
633
ITv^l
11706002-
11707005
11706002-
11707005
11706003-
11706002
11706003-
11706002
11706003-
11706002
11706004-
11706003
11706004-
11706003
11706004-
11706003
11706005-
11706004
11706006-
11706005
11706006-
11706005
11707005-
11702001
11707005-
11702001
11707005-
11702001
11711001-
11706006
11711001-
11706006
11711001-
11706006
11712001-
11711001
11712002-
11712001
11712002-
11712001
11712003-
11712002
4/16/2013
11:28
5/3/2013
17:05
1/31/2013
11:41
4/16/2013
11:33
5/3/2013
16:58
1/31/2013
11:53
4/16/2013
11:39
4/16/2013
11:43
1/31/2013
12:02
1/31/2013
12:11
4/16/2013
11:48
1/28/2013
11:43
1/28/2013
11:46
4/16/2013
11:22
1/31/2013
12:23
4/16/2013
11:54
4/16/2013
12:03
1/31/2013
12:30
1/31/2013
12:50
4/16/2013
12:09
1/31/2013
12:57
HlMJl
250
250
350
350
350
350
350
250
150
150
150
250
250
250
150
250
250
150
250
150
250
BT^^JlTlB
HI
^Um^2^l
155
368
218
275
350
375
356
233
188
239
105
236
236
191
210
220
306
257
172
202
191
mm
Assess-
ment
9
9
5
8
9
7
8
9
10
7
8
0
0
7
8
9
9
9
9
9
9
Status
Good
Good
Fair
Good
Good
Good
Good
Good
Good
Good
Good
Block
Block
Good
Good
Good
Good
Good
Good
Good
Good
Date
4/30/2013
5/2/2013
xxxxxx
4/30/2013
5/2/2013
xxxxxx
xxxxxx
4/30/2013
3/5/2013
3/5/2013
4/30/2013
xxxxxx
2/1/2013
4/30/2013
2/28/2013
3/4/2013
4/30/2013
4/30/13
2/28/13
4/30/13
2/1/13
EH
Findings
__
Roots Med
Fine roots
xxxxxxx
(see Text)
Root Ball
(see Text)
Roots fine
(see Text)
xxxxxxx
xxxxxxx
Roots fine
Roots Med
Slight
structural
Slight
structural
xxxxxxx
(see Text)
Roots Lt /
Med
(see Text)
Root Ball
(see Text)
Roots Med
Roots Med
No Issues
Light O&M
Surface
damage
Roots fine
No issues
3-3
-------
Demonstration oj'SL-RAT™Report
Section ^-Technology Demonstration Results
^^s
^m*^l
682
683
637
684
685
692
639
687
688
689
691
640
695
641
642
618
644
645
635
11712003-
11712002
11712004-
11712003
11712005-
11712004
11712005-
11712004
11712006-
11712005
11712006-
11712005
11713003-
11713002
11713003-
11713002
11713004-
11713003
11713004-
11713003
11713006-
11712006
11713018-
11713003
11713018-
11713003
15016001-
11713004
15016002-
15016001
11702002-
11702003
11706007-
11705010
11706007-
11705010
11712004-
11712012
4/16/2013
12:15
4/16/2013
12:21
3/7/2013
11:51
4/16/2013
12:27
4/16/2013
12:32
4/17/2013
12:57
3/7/2013
13:00
4/16/2013
12:49
4/16/2013
12:58
4/16/2013
13:07
4/17/2013
12:53
3/7/2013
13:13
4/17/2013
14:42
3/7/2013
13:37
3/7/2013
13:45
1/28/2013
10:52
3/20/2013
9:59
3/20/2013
10:06
3/7/2013
11:12
250
250
250
150
150
50
350
350
250
250
50
250
50
250
250
250
350
350
150
EEHIffllIgH
Pipe Assess- Status
Length ment
(feet)
188
205
93
112
122
110
257
413
103
90
132
68
246
143
117
322
209
209
165
9
10
9
9
9
8
7
5
10
9
8
9
7
5
9
8
10
8
10
Good
Good
Good
Good
Good
Good
Good
Fair
Good
Good
Good
Good
Good
Fair
Good
Good
Good
Good
Good
4/30/13
5/1/13
2/28/13
5/1/13
2/28/13
5/1/13
3/1/13
5/1/13
3/1/13
5/1/13
5/3/13
5/3/13
xxxxxx
3/1/13
3/15/13
Not done
Not done
Not done
Not done
EH
Findings
Roots fine
Light
deposits
Light
deposits
Light
deposits
No issues
No issues
Sideline
splash at Rx
Gusher/
Light
deposits
Light
deposits
Sideline
splash atTx
- no effect
No issues
No issues
xxxxxxx
Sideline
(not
splashing)
may affect
Rx
No issues
NA
NA
NA
NA
3-4
-------
Demonstration oj'SL-RAT™Report
Section ^-Technology Demonstration Results
636
11712005-
11712012
3/7/2013
11:43
150
Assess- Status Date
273
Good
Not done
NA
693
11712006-
11713005
4/17/2013
14:09
350
352
Good
Not done
NA
694
11713003-
11713014
4/17/2013
14:38
150
347
Good
Not done
NA
696
11713004-
15016002
4/17/2013
14:55
250
381
10
Good
Not done
NA
697
11713006-
11713001
4/17/2013
15:25
250
74
10
Good
Not done
NA
Of the fifty-four (54) SL-RAT assessments supported by CCTV, forty-nine (49) assessments were in the
upper range (7 to 10), three (3) in the medium range (4 to 6), and two (2) in the low range (0 to 3). No
major structural defects were found during the CCTV inspections (no PACP Structural Grades of 4 or 5
defects). However, numerous minor PACP O&M defects were identified.
3.1.1 Upper-Range Score Discussion
Of the forty-nine (49) upper range scores, forty-two(42) assessments were found to correlate with the
CCTV inspection results. For the remaining seven (7) of the forty-nine (49) upper range SL-RAT
assessments, the CCTV inspection identified roots in the pipe perhaps warranting a lower assessment
score. These seven (7) readings represent only four (4) individual pipe-segments. The root intrusion on
three (3) of the four aforementioned pipe-segments was estimated to be less than 50%. In all cases the
CCTV robot transporter was able to pass through or around the roots, indicating the root density was
limited. The remaining pipe-segment (11706003-11706002), which registered an 8 reading, had
previously registered a five (5) reading due to roots. Subsequently, this segment was root cut and a
follow up CCTV inspection showed an 80% root ball (new) about three feet from the manhole.
3.1.2 Medium-Range Score Discussion
Of the three (3) medium range scores, the segment discussed above registered a score of five (5) due to
roots. In addition, two other sections also registered a five (5), but no significant issues were identified
with these pipe segments. At one location, based on the inspection video, a sideline pipe was seen
splashing into the manhole where the RX unit was deployed. This location had previously registered a
reading of seven (7). At the other location, a sideline was also observed coming out of the manhole.
These sidelines may have interfered with the results.
3-5
-------
Demonstration ofSL-RAT™Report Section ^-Technology Demonstration Results
3.1.3 Low-Range Score Discussion
The two (2) low range assessments were on the same pipe-segment (11707005-11702001) and were
conducted within minutes of each other. In both cases, the SL-RAT assessment was a zero (0) indicating
that essentially no acoustic energy was being received at the RX from the TX transmission. The pipe
segment was root cut prior to CCTV inspection. A subsequent CCTV inspection conducted a few days
after the root cut operation indicated only light and medium roots in the pipe. A follow up SL-RAT
assessment conducted two and half months later registered a seven (7). A CCTV inspection was
conducted two weeks later that identified a root-ball in the pipe. During this CCTV inspection, the robot
transporter was able to pass through or around the roots, indicating that the root density was limited.
3.2 Hunt Road Area CCTV/SL-RAT Assessment Summary
The Hunt Road Evaluation area consists mainly of off-road sewers, through a wooded area serving
several residential subdivisions. The terrain on the periphery has very steep slopes and access to the
manholes is provided by an unpaved path cut through the area from the downstream location. The
alignment of the sewer is along the path which is adjacent to an unnamed creek in the East Branch of
the Mill Creek watershed.
In this study area, the SL-RAT operation and inspections were performed between May 2013 and June
2013. Originally, 40 sewer segments were defined for inclusion in the evaluation area. Only twenty-six
(26) sections were inspected using CCTV. Based on the CCTV inspections, no sewer segments were
found in need of cleaning and two (2) segments were found with structural issues, neither of which
resulted in obstruction of the pipe. Only nineteen (19) of the sewer segments were assessed with the SL-
RAT and these assessments are used for the evaluation. The seven (7) pipe-segments that were
inspected by CCTV, but not inspected using the SL-RAT are not reported in this dataset.
Table 3-2 presents the SL-RAT test results and the correlating CCTV inspection findings of the nineteen
(19) segments at the Hunt Road site.
3-6
-------
Demonstration oj'SL-RAT™Report
Section ^-Technology Demonstration Results
Table 3-2. Summary of SL-RAT and CCTV Results Hunt Road.
SL-RAT Pipe Segment ID
771
772
773
830
834
831
832
833
835
836
837
770
774
822
823
824
825
826
827
828
44705004-44706017
44705004-44706017
44705005-44705004
44706004-44707026
44706009-44706010
44706010-44706004
44706011-44706010
44706012-44706011
44706013-44706010
44706014-44706013
44706015-44706014
44706017-44706015
44712001-44705005
44712002-44712001
44712007-44712002
44712008-44712007
48209013-44712008
48209014-48209013
48209015-48209014
48209016-48209015
SL-RAT Test
Date/Time
5/13/2013 11:43
5/13/2013 13:02
5/13/2013 13:06
6/3/2013 15:02
6/3/2013 16:29
6/3/2013 15:14
6/3/2013 15:21
6/3/2013 15:43
6/3/2013 16:39
6/3/2013 17:02
6/3/2013 17:25
5/13/2013 11:36
5/13/2013 13:13
6/3/2013 11:26
6/3/2013 11:37
6/3/2013 11:47
6/3/2013 11:55
6/3/2013 12:07
6/3/2013 12:17
6/3/2013 12:25
Input Pipe GPS Pipe SL-RAT Pipe CCTV CCTV Findings
Length (feet) Length (feet) Assessment Status Date
150
150
50
150
150
150
50
250
350
350
150
250
350
350
150
150
350
350
250
250
126
194
29
253
27
183
36
351
232
314
60
133
201
819
219
151
24
593
164
206
7
8
9
8
8
8
8
9
9
10
8
7
9
9
9
9
8
10
10
9
Good
Good
Good
Good
Good
Good
Close
Good
Good
Good
Good
Good
Good
Good
Good
Good
Good
Good
Good
Good
5/28/13
xxxxxx
5/28/13
6/12/13
6/12/13
6/12/13
6/13/13
6/12/13
6/12/13
5/28/13
5/28/13
5/28/13
5/28/13
5/28/13
5/28/13
5/28/13
5/28/13
6/10/13
6/10/13
6/10/13
No Log - Minor O&M
xxxxxx
Minor deposits
throughout
Deposits - Water Level
25%
No issues
Minor deposits
throughout
No issues
No issues
No issues
Minor structural
issues
Minor grease
Deposits - Water Level
45%
No Log- Minor O&M
Minor grease &
deposits
Minor structural
issues
Minor deposits
Minor deposits
No log- minor O&M
No issues
No issues-Water Level
50% at DS manhole
3-7
-------
Demonstration oj'SL-RAT™Report
Section ^-Technology Demonstration Results
Several sewer segments were documented to have high PACP O&M ratings; however, those scores were
due to continuous minor grease or encrustations/deposits in the pipe.
All SL-RAT assessments in the upper range (7 tolO) were consistent with the CCTV inspection findings.
Two segments were assessed at the low end of the upper range, i.e., an assessment of seven (7). One of
the two segments that registered a SL-RAT score of seven (7) had a follow up assessment (less than two
hours later) and returned a score of eight (8). The other segment with an SL-RAT assessment of seven (7)
had grease deposits throughout the length of pipe, as did some of the other segments that returned
higher scores. Based on the CCTV inspection for this pipe-segment, a water level at 45% was reported
due to a sag in the 12-inch diameter pipe. As indicated by the vendor, Table 1-1, sags can result in lower
assessment scores.
3.3 Greenhills Area - Rapid Deployment Evaluation Summary
As mentioned previously in Section 2.4, the Greenhills study area involved SL-RAT measurements at 53
pipe-segments representing approximately 9,500 linear feet of pipe with pipe sizes of 8" and 10"
diameters. A goal of this study area was to evaluate the time required to perform the acoustic
inspections with the SL-RAT. The SL-RAT inspections were performed on May 8, 2013 (between 9:59 AM
and 1:29 PM) and May 10, 2013 (between 9:12 AM and 10:37 AM) which computes to a total
assessment time of 6 hours, or effectively one day (including time for travel to field and equipment
setup). For 51 of the 53 measurements, the time to conduct the SL-RAT inspections was either 79 or 80
seconds. The other two inspections required 111 seconds to complete. These two inspections resulted
in low range assessment scores. Longer inspection times are typically required for obstructed pipe
segments. The time interval between inspections was also evaluated by using the time/date stamp
recorded by the SL-RAT at the start of each inspection. The time interval evaluation includes
• Travel time between segment locations within the study area
• Inspection setup time, i.e., removing the manhole cover and inserting the SL-RAT unit
• Measurement time.
The time intervals between inspections are summarized in Table 3-3, with an average time interval of 5
minutes and 33 seconds. Since the inspections were conducted over a two day interval, there are a total
of 51 time intervals to conduct the 53 inspections.
Table 3-3. Summary of Time Interval between Inspections for Greenhills.
Occurrences
% of Total
37
73
14
3-8
-------
Demonstration oj'SL-RAT™Report
Section ^-Technology Demonstration Results
The assessment scores for the SL-RAT inspection are summarized in Table 3-4. Based on the inspection
results, there are forty-seven (47) segments in the high range (7-10), 4 in the medium range (4-6) and 3
in the low range (0-3), corresponding to 88.7%, 7.5% and 3.8% of the total number of segments,
respectively. Based on the CMU SL-RAT action plan (Fishburne, J. 2011) this implies that 88.7% of the
pipes are considered clear with no additional maintenance action taken. The assessments between 0 to
4 or 5.7% of the pipes would be cleaned and the assessments with 5 or 6, another 5.7%, would either be
conservatively cleaned, CCTV inspected or placed on a watch list depending on the availability of
maintenance resources. The three pipe segments with scores less than 5 represent approximately 650
feet of linear pipe, i.e., 6.9% of the total pipe length. The six pipe segments with scores less than 7
represent approximately 1,400 feet of linear pipe, i.e., 14.7% of the total pipe length. Four pipe
segments were assessed using CCTV. Table 3-5 presents a summary of these results.
Table 3-4. Summary of SL-RAT Assessment Scores for Greenhills.
Number of
Occurrences
16
22
Table 3-5. Summary of SL-RAT and CCTV Results Greenhills.
713
SL-RAT Pip<
Record Segment
No. ID
31602004-
31601005
i Pipe Assessment
ih Length
(feet) (feet)
5/8/2013
10:05
250
110
Good
CCTV Findings
5/10/13
90% root at one
of the seven taps
734
31602007-
31602008
5/8/2013
12:09
150
103
Fair
6/17/13
Offset joint,
heavy roots at
one tap, grease
and deposits
needs cleaning
717
31601005-
31601001
5/8/2013
10:42
250
199
Good
5/10/13
Encrustation,
intruding seal
material, roots
on tap
743
31602008-
31602009
5/8/2013
12:51
350
304
Good
6/17/13
Deposits, roots
medium at joint
3-9
-------
Demonstration oj'SL-RAT™Report
Section ^-Technology Demonstration Results
3.4 Miscellaneous Pipe Evaluation Summary
Except for the one pipe segment in the Galia Drive study area, there were no other pipes found during
the study that were significantly blocked. In order to assess improvements in SL-RAT reported scores in
areas where blocked pipes were expected or reported, thirty (30) pipe-segments were randomly
evaluated during the month of August 2013. Based on the SL-RAT inspection, one pipe segment (ID -
54815003-54815004) was found that scored a zero on August 1, 2013. The pipe was subsequently
cleaned and re-evaluated on August 30, 2013.The SL-RAT re-evaluation indicated the pipe segment was
clean based on an assessment score of 9. The remaining 29 pipe-segments were found to be not
completely blocked, i.e., had SL-RAT assessments greater than zero.
3.5 PACP and SL-RAT Score Correlation
As noted previously in Section 1.3, the de-facto industry standard for observation and defect coding for
sewer pipe CCTV inspection is the NASSCO PACP methodology. During the evaluation phase of the SL-
RAT results, an attempt was made to correlate the SL-RAT output values to the defect coding recorded
during the CCTV inspection and subsequent PACP condition grading. It was believed that the output
results on both the low and high-ends of the range for the SL-RAT could potentially correlate to the
PACP ratings. However, it was unknown if the intermediate SL-RAT results would correlate with the
PACP defect scores.
To perform a correlation, the PACP Segment Grade and Overall Pipe Rating (Rating), the Quick Rating,
and the Pipe Ratings Index (Index) calculations of pipe condition were collectively evaluated in an
attempt to construct a method of comparison to the SL-RAT's numerical scaled-output value. Both the
Rating and Index provide a single numerical assessment for a pipe segment as discussed in detail in
Section 2.3. Examples of the PACP O&M scores obtained from the data gathered during this field study
are presented in Table 3-6.
Table 3-6. Example of PACP Assessment O&M Score - Galia Drive Data.
PACP O&M Score from CCTV Reports
Segment
Grade Grade
1 2
11702001-
11702002
0
30
Rating Quick Index SL-RAT
30
2BOO
2.0
11707005-
11702001
11
27
5133
1.687
5
The first pipe-segment number 11702001-11702002 has a higher rating (O&M Rating - 30 and Index -
2.0) compared to the second pipe segment number 11707005-11702001 (O&M Rating - 27 and Index
3-10
-------
Demonstration ofSL-RAT™Report Section ^-Technology Demonstration Results
1.68) due to a high number on Grade 2 defects. In comparison, the SL-RAT scores are at the opposite
ends of its computed scale. This result is not surprising to an operator who understands the PACP score
nuances because the second pipe-segment has one Grade 5 defect due to a root ball that would block
the transmission of the SL-RAT acoustic signal as well as obstruct the flow. Whereas the minor grease
encrustation along the first pipe segment resulted in PACP Grade 2 defect score of 30, this would have
minimal impact on acoustic transmission as well as the flow.
Another example of numerically incompatible results is the case of a PACP code matrix for a deposit of
grease greater than 30% in a pipe, which would be given an O&M grade of 5. Following the PACP scoring
methodology, a completely obstructed pipe due to a grease blockage would also be given a PACP score
of 5. In the first instance, the SL-RAT is likely to return a score in the mid- range of the output scale
(between 4 and 6); however, the second instance would likely return a low SL-RAT output of (between 0
andl), meaning almost no sound would be received at the SL-RAT's RX unit.
In summary, to perform a correlation between PACP and SL-RAT scores, each discrete defect recorded
on the PACP inspection log must be individually compared to see how it would impact the SL-RAT
results. Therefore, a simple algorithmic approach for comparing PACP and SL-RAT score was not
possible.
3.6 SL-RAT Data Visualization and Post-Processing Tools
In addition to the on-screen SL-RAT reported scores in the field, InfoSense also provides additional data
visualization and post processing tools. The visualization tool provided by InfoSense is a Google Earth
based data viewing option where the SL-RAT measurements can be visualized. Figure 3-1 presents a
summary visual of the Galia Drive results using Google Earth and the Keyhole Markup Language (KML)
file generated by InfoSense. To utilize this tool, the SL-RAT data needs to be uploaded using their
proprietary Sewer Line Diagnostic OrGanizer (SL-DOG) software-as-a-service (SaaS) application to a
secure online environment from a properly configured web-enabled computer.
3-11
-------
Demonstration oj'SL-RAT™Report
Section ^-Technology Demonstration Results
Upper-Range Score
Medium-Range Score
Low-Range Score
Figure 3-1. Summary visual of SL-RAT Results Galia Drive.
In addition to the visualization, post-processing and verification can also be performed. Varying stages of
verification are available based on customer requirements. The verification process has two objectives:
1. Verify the pipe segment length used in evaluating the SL-RAT condition assessment. The SL-DOG
uses the reassessed pipe length to reevaluate the condition assessment.
2. Verify the utility's pipe segment ID associated with the SL-RAT condition assessment.
The length of pipe impacts the amount of acoustic energy that is expected to pass through a pipe-
segment. The larger the pipe length, less of the transmitted energy from the TX unit is expected to travel
through and be received by the RX unit in the field. At the time of assessment, the SL-RAT algorithm
requires an estimate of the segment length to conduct the assessment. During the in-field
measurement, the operator enters the pipe length (+ 50 feet) used in the initial on-site evaluation. The
SL-DOG post-processing allows the reevaluation of the assessment based on an updated pipe length. As
an example, if an operator inadvertently enters 50' for a 250' pipe segment, the recalculated acoustic
assessment score may be higher than the field reported value on the SL-RAT device because less sound
energy is expected to pass through a longer pipe. The SL-DOG can adjust the field-reported assessment
score based on the corrected length. A more detailed discussion of this option from InfoSense is
presented in Appendix A.
It should be also noted that the GPS-based positioning is prone to errors especially in off-road areas
where significant vegetation (i.e., canopy) and topographic features (e.g., steep slopes) are present
(Rumble and Lindzey, 1997). Therefore, the pipe lengths must not be corrected simply based on the GPS
3-12
-------
Demonstration ofSL-RAT™Report Section ^-Technology Demonstration Results
data collected during the assessment. The GPS mapping errors of one pipe-segment assessed in Galia
road is also depicted in Appendix A (Figure 2).
3.7 SL-RAT Operator Feedback
As a part of this evaluation, MSDGC field personnel were asked to provide input on the SL-RAT
performance from an operator perspective. The following is a categorized summary of their
observations:
3.7.1 Usability
SL-RAT is a wireless device that is easy to operate, is very rugged, batteries last awhile, and only two
pieces of equipment have to be carried. Every manhole needs to be accessed in order to perform a test.
The device is loud when standing at the manhole with the TX unit that contains the speaker. When using
acoustic devices, understanding the exposure to excessive noise levels is important for the operator's
safety. The vendor, InfoSense, has evaluated the sound level experienced by the SL-RAT TX operator
under normal operation. Multiple sound pressure level (SPL) measurements were made within a two
foot radius and at a height of four feet above a manhole while the TX unit was operating. The averaged
results for each of the 16 tones used to conduct an SL-RAT inspection are depicted in the graph in Figure
3-2. Based on Occupational Safety & Health Administration (OSHA) requirement (OSHA, 1910) for noise
exposure, the permissible exposure for 85dBA is 16 hours per day and for 88 dBA is 10.6 hours per day.
Using the data from the graph in Figure 3-2, the operator is exposed to an SPL between 85 to 88dBA for
3 seconds during each tone sequence. There are typically 5 tone sequences per pipe segment
inspection. As a conservative estimate, assuming 12 inspections per hour over an eight hour work day,
the total exposure time for SPL levels between 85 to 88 dBA is 24 minutes, significantly less than the
10.6 hours permissible by OSHA at the 88dBA level. For comparison, a vacuum truck's average acoustic
noise emission level at 50 feet is 85dBA with a usage factor of 40% (USDOT, 2006).
3.7.2 Data Quality
The results are very easy to interpret. The operator should be aware that the results sometimes will
depend upon the environment. For example, in the case of data received when testing
sewers/manholes that have other inlets tied into the manhole, the result may come back as bad. The
operator must be aware of these types of site-specific nuances while interpreting results.
3.7.3 Software
Downloading the information is quick. The operators did have issues with using the software, but were
always able to resolve these issues without having to contact the vendor. As indicated in Section 1.6, the
initial onsite training by the vendor was hampered primarily by weather. This limited the onsite SL-DOG
software training and did not allow the vendor to provide hands-on training of the correct steps for
downloading the measurement data from the device. Even though the software is straight-forward to
use, there are key steps required for its correct operation, such as ensuring measurement data stored
on the SL-RAT TX unit is transferred to the RX unit via the unit's RF interface.
3-13
-------
Demonstration oj'SL-RAT™Report
Section ^-Technology Demonstration Results
on
CO ' "
Q. c-
CO es
en
air
4*
3
C
[
n
b
:
n
:
n
c
?
5 n c
:
n
n c
,
D
]
6 8 10 12
Tone Sequence Number
14
16
Figure 3-2. Typical Sound Pressure Level (SPL) Experienced by the SL-RAT Transmitter Operator for Each
One Second Tone.
3-14
-------
Demonstration oj'SL-RAT™Report
Section 4-Summary and Conclusions
Section 4—SUMMARY AND CONCLUSIONS
For the purposes of this report, three ranges of SL-RAT output scores have been used to determine if the
pipe is open (high), there is a blockage (low), or if additional investigation is needed (medium). The
actual output numbers that make up these ranges can be flexible based on the user's experience and
the policies established by individual organizations. As reported previously in Section 3.0, for the
purposes of this report, the SL-RAT score ranges are mapped as follows: 0-3 (low), 4-6 (medium), and 7-
10 (high). A zero reading is reliable in identifying a blocked pipe and a 10 indicates the pipe is open and
no further cleaning or investigation is needed. The two detailed study areas (Galia Drive and Hunt Road)
did not have a substantial number of pipe segments with a range of defects that could be used to
statistically define these ranges. However, the data indicates that the extreme scores are reliably
assessed in the vast majority of the cases. In general, outputs of 7 to 10 reliably indicated that the pipe
was open and free of significant obstructions.
Overall, the use of SL-RAT as a pipe-condition assessment tool needs to be evaluated in context with
the existing tools available to wastewater utilities. Figure 4-1 presents a graphic summary of where the
SL-RAT as a sewer pipe inspection tool is likely to fit into a wastewater utility's "tool-box."
HIGH
O
V)
0)
o
0)
Q.
V>
LOW
Wastewater Pipe
Condition Assessment
Applications
Pipe Wall Defect
Detailed
Pipe Profiling
s
LOW
Relative Cost
HIGH
Figure 4-1. Sewer Pipe-Condition Assessment Tools (Adapted from: InfoSense, 2013).
4-1
-------
Demonstration oj'SL-RAT™Report
Section 4-Summary and Conclusions
4.1 Inspection Cost per Foot Analysis
The costs for CCTV inspection and cleaning of small diameter pipelines can vary widely from pipe to pipe
and from utility to utility. There are many variables that affect the cost of pipe inspection for any given
utility. For MSDGC, cost variables for CCTV inspection of small diameter pipes include factors such as
personnel costs, travel costs, setup, planning and data management costs. Certain locations, that are
not in the public right-of-way, in easements or difficult to access due to off-road locations, often require
special arrangements or specially equipped off-road vehicles. Tables 4-1 and 4-2 summarize the average
cost of on-road and off-road CCTV inspections, respectively, for MSDGC.
Table 4-1. MSDGC On-Road CCTV Inspection Costs.
S. No.
1
2
3
4
Labor/Equipment
Crew
CCTV Truck
Polaris ATV
Setup, Planning
and Data
Management
unit
Cost/Hour
$38.46
$25.00
$80.00
$100.00
Quantity
2,000
1,000
200
1,000
Total
Average Daily CCTV Production
Average Annual CCTV Production
CCTV Inspection Cost
Annual Cost
$76,923
$25,000
$16,000
$100,000
$217,923
1000
130,000
$1.68
Assun.ptions
Assume 2 persons and annual
burdened salary of $80,000
per person, dedicated ~l/2
time (1,000 hours/year each)
Assuming 1,000 hours of
average operation per year
Assuming 200 hours of
operation per year needed for
special access at select
locations
Includes Multiple Personnel,
Work Order management, GIS
software and Data
Management Costs, QA/QC of
CCTV data
$ per year
(computed from above)
feet/day (MSDGC estimate)
feet/per year
(1/2 time 130 workdays - 26
weeks, 5 days/week)
$/foot of on-road pipe
inspected
4-2
-------
Demonstration oj'SL-RAT™Report
Section 4-Summary and Conclusions
Table 4-2. MSDGC Off-Road CCTV Inspection Costs.
S. No.
1
2
3
4
Labor/Equipment Unit Quantity
Crew
CCTV Off-Road
Tractor
Polaris ATV
Setup, Planning
and Data
Management
$38.46
$71.50
$80.00
$100.00
2,000
1,000
200
1,000
Total
Average Daily CCTV Production
Average Annual CCTV Production
CCTV Inspection Cost
Annuals,
$76,923
$71,500
$16,000
$100,000
$264,423
1000
130,000
$2.03
Assumptions
Assume 2 persons and annual
burdened salary of $80,000
per person, dedicated ~l/2
time (1,000 hours/year each)
Assuming 1,000 hours of
average operation per year
Assuming 200 hours of
operation per year needed for
special access at select
locations
Includes Multiple Personnel,
Work Order management, GIS
software and Data
Management Costs, QA/QC of
CCTV data
$ per year
(computed from above)
feet/day (MSDGC estimate)
feet/per year
(1/2 time 130 workdays - 26
weeks, 5 days/week)
$/foot of off-road pipe
inspected
The Water Environment Research Foundation (WERF) and EPA (WERF, 1997, EPA, 1999), have reported
an average nationwide CCTV inspection cost of $4,600 per mile or $0.87 per foot. In the above
referenced EPA report, ADS Environmental Services (ADS, 1998) reports CCTV inspection cost range of
$1,000 to $11,450 per mile, which at the high end computes to $2.17 per linear foot. The most recent
WERF report (WERF, 2013) reviewed the trends and cost drivers of CCTV inspection as a function of
pipeline diameter, project length, and regional location. WERF reported that the majority of the CCTV
projects for inspecting pipelines fell under $3.00 per foot regardless of pipe size. Furthermore, the WERF
report indicated that the majority of the projects reported a unit cost of less than $2.00 per foot, once
the overall inspected pipe length surpassed 5,000 feet. The report concluded that 5,000 linear feet of
pipe is the threshold for attaining savings from economies of scale. Comparatively, Table 4-3
summarizes the expected cost of both on-road and off-road SL-RAT inspections for MSDGC.
4-3
-------
Demonstration oj'SL-RAT™Report
Section 4-Summary and Conclusions
Table 4-3. SL-RAT On/Off-Road Inspection Costs.
S. No.
1
2
3
3
4
Labor/Equipment
Crew
SL-RAT Purchase
Price
Regular Truck
Polaris ATV
Setup, Planning
and Data
Management
Unit Quantity Annual Cost
Cost/Hour
$38.46
$20.00
$6.00
$80.00
$100.00
2,000
1,000
1,000
200
500
Total
Average Daily SL-RAT Production
Average Annual SL-RAT Production
SL-RAT Inspection Cost
$76,923
$20,000
$6,000
$16,000
$50,000
$168,923
9,500
1,235,000
$0.14
Assumptions
Assume 2 persons and annual
burdened salary of $80,000
per person, dedicated ~l/2
time (1,000 hours/year each)
$20,000 purchase price cost
of SL-RAT spread over 1000
hours of use. Not amortized
for 3-years expected life
A regular truck will be needed
to carry personnel to site
Assuming 200 hours of
operation per year needed for
special access at select
locations
Assumes these costs will be
halved compared to CCTV
inspection. Includes Multiple
Personnel, Work Order
management, GIS software
and Data Management Costs,
QA/QC of SL-RAT data
$ per year
(computed from above)
feet/day
(based on Greenhills data)
feet/per year
(1/2 time 130 workdays - 26
weeks, 5 days/week)
$/foot of on-road and off-road
pipe inspected
Although the inspection output or detail provided by SL-RAT is not equivalent to a CCTV report, the
order of magnitude cost-per-foot savings makes a good case for using the SL-RAT as a tool to perform
screening type assessments (prior to the deployment of the more expensive condition assessment
equipment or cleaning).
4-4
-------
Demonstration ofSL-RAT™ Report Section 4-Summary and Conclusions
4.2 Rapid Deployment Capability
The majority of the pipes selected for CCTV inspection, acoustic inspection and cleaning for this
demonstration project were off-road difficult to access, inspect, and assess. The objective of the project
was to demonstrate the performance of the acoustic inspection technologies rather than evaluate the
cost of performance. It can be reported that one of the key advantages of SL-RAT is the rapid
deployment feature using portable equipment that can result in significant cost-savings to the utilities in
comparison with traditional inspection methods such as CCTV inspection, especially when "screening-
type" assessments, such as those to determine cleaning needs, are the goal of the inspections.
The majority of the SL-RAT test durations for this project were 79 or 80 seconds. Two test durations
were greater than 80 seconds; in both cases, the pipe was substantially blocked with roots. When
compared to CCTV inspection rates of 30 feet/minute, the rapid assessment capabilities of the acoustic-
based SL-RAT system is apparent. While this tool does not eliminate the need for using CCTVs in
assessing pipes, it can limit the deployment of the more expensive CCTV resources to focus on critical
pipe-segments.
4.3 Opportunity to Refocus Critical Resources Deployed for Pipe Cleaning
As reported previously in Section 1.1, cleaning and inspecting sewer pipes is essential for utilities to
operate and maintain a properly functioning collection system and avoid SSOs. For many utilities, sewer
cleaning and inspection programs are generally part of a larger CMOM program. The routine
maintenance of a sewer system often includes sewer system cleaning, root removal/treatment, and
cleaning/clearing of sewer mainline stoppages. However, understanding where and when to perform
cleaning activities is not necessarily a straight-forward task. The three common approaches adopted by
utilities are as follows:
4.3.1 Routine Cleaning
Some wastewater utilities clean their sewer system as a matter of course without knowing in advance
whether the system or portions of the system require cleaning. Pipes with blockages receive the same
attention and resources as those with potentially no cleaning needs. In this approach, the use of staff
and equipment is not optimized consuming staff time and resources that could be directed to other
more productive maintenance activities.
4.3.2 Directed Cleaning
In an attempt to direct maintenance staff and cleaning equipment to just those pipes in a sewer system
that require attention, some agencies attempt to identify cleaning needs by conducting inspection of
the sewers prior to cleaning. These pre-cleaning inspections are conducted using various approaches
and equipment to varying degrees of success, efficiency and speed.
4.3.3 Reactive Cleaning
For many wastewater utilities, staff-time is directed solely towards reactive cleaning where staff and
equipment are deployed to address blockages, spills or other emergencies.
4-5
-------
Demonstration ofSL-RAT™ Report Section 4-Summary and Conclusions
4.4 Conclusion
The emergence of acoustic sewer inspection technologies, like SL-RAT, as rapid deployment, low-cost,
reliable, pre-cleaning assessment tools is focusing growing attention on the potential for more cost-
effective sewer cleaning programs. Through the ease of deployment, reduction of cost, increases in
reliability of these inspection approaches, combined with the potential for reducing the "cleaning of
clean pipes," significant cost savings are attainable. As utilities apply these new inspection technologies,
they can move towards implementing sewer cleaning programs that consist of planned directed and
quick response, reactive cleaning. Also, these cost savings can be realized while improving collection
system performance and the protection of public health and water quality.
The results of this demonstration project reveal the potential for more cost-effective sewer cleaning
programs. The site specific pre-cleaning assessment inspection costs resulting from this project and
MSDGC's historic practices for CCTV (on-road), CCTV (off-road), and SL-RAT (on- and off-road) are
$1.68/ft., $2.03/ft., and $0.14/ft., respectively. So, for pre-cleaning assessment, the application of the
SL-RAT can reduce MSDGC's costs by $1.54/ft. for on-road sewers and $1.89/ft. for off-road sewers. In
addition, by moving to a sewer cleaning program predominated by planned directed cleaning, MSDGC
can save $2.00/ft. by reducing its "cleaning of clean pipe." In total, when costs of conventional CCTV
inspection and cleaning are combined, for each pipe segment that is deemed "clean" using the SL-RAT,
MSDGC can save $3.54/ft. for on-road sewers and $3.89/ft. for off-road sewers.
The results of this demonstration of the SL-RAT show promise for its application as a tool for cost-
effective, pre-cleaning assessment and post-cleaning quality assurance. The application of the SL-RAT in
an overall collection system O&M program should enable wastewater utilities to optimize their sewer
cleaning efforts and free up valuable resources to more effectively implement critical CMOM and asset
management programs.
4-6
-------
Demonstration oj'SL-RAT™Report Section 5-References
Section 5—REFERENCES
ADS Environmental Services (1998). "Sewer Evaluation Services." Reported to be accessed by EPA in June,
1998.
EPA (1999). Collection Systems O&M Fact Sheet Sewer Cleaning and Inspection. U.S. Environmental
Protection Agency, Office of Water, Washington, DC. Report No. 832-F-99-031, September 1999.
EPA (2005). Guide for Evaluating Capacity, Management, Operation, and Maintenance (CMOM)
Programs At Sanitary Sewer Collection Systems. U.S. Environmental Protection Agency, Office of
Enforcement and Compliance Assurance, Washington, DC. Report No. 305-B-05-002, January
2005.
EPA (2009). Condition Assessment of Wastewater Collection Systems. State of Technology Review
Report. U.S. Environmental Protection Agency, Office of Research and
Development, Washington, DC. Report No. 600-R-09-049, May 2009.
EPA (2012). Sanitary Sewer Overflows and Peak Flows. U.S. Environmental Protection Agency (website)
(Accessed 2014).
EPA (2012b). Quality Assurance Project Plan, Category IV Measurement Project - Condition Assessment
of Wastewater Collection Systems. U.S. Environmental Protection Agency, Office of Research and
Development. QA ID W-17354-QP-1-0, dated October 2012, Approved November 2012.
Fishburne, J. (2011). Using Acoustical Transmissivity as a Gravity Sewer Maintenance Programming Tool.
Water Environment Federation (WEF) Collection Systems Conference, Raleigh, NC, June 2011.
InfoSense (2013). Rethinking Collection System Maintenance with the Sewer Line Rapid Assessment Tool
or SL-RAT™. Pumper and Cleaner International Environmental Expo, Indianapolis, IN, February
2013.
OSHA, 1910. Noise Exposure computation. 1910.95 App A. Occupational Health and Environmental
Control, Standards - 29 CFR, Occupational Safety & Health Administration
Rumble, M.A., and Lindzey, F. (1997). Effects of Forest Vegetation and Topography on Global
Positioning System Collars for Elk. American Congress on Surveying and Mapping (ACSM) and
American Society for Photogrammetry & Remote Sensing (ASPRS) Joint Annual Convention &
Exposition (Technical Paper), Seattle, Washington April 7-10, 1997.
Sprague, J. (2007). Metropolitan St. Louis Sewer District System Wide Cleaning Program, Presentation
dated July 19, 2007.
5-1
-------
Demonstration oj'SL-RAT™Report Section 5-References
USDOT (2006). Construction Noise Handbook, DOT-VNTSC-FHWA-06-02, U.S. Department of
Transportation Research and Innovative Technology Administration, August 2006.
WERF (1997). Benchmarking Wastewater Operations - Collection, Treatment, and Biosolids
Management. Water Environment Research Foundation (Project 96-CTS-5).
WERF (2013). Cost Information for Wastewater Pipelines - Synthesis Report. Water
Environment Research Foundation, Alexandria, VA.
5-2
-------
Demonstration ofSL-RA 7™ Report Appendix A
APPENDIX A-SL-DOG CONDITION ASSESSMENT DATA
VERIFICATION
During the in-field condition assessment of a pipe segment, the SL-RAT collects data to assist in
verification. The verification is performed as an automated post process through the SL-DOG. Varying
stages of verification are available based on the requirements of the utility. This verification process has
two objectives:
1. Verify the pipe segment length used in evaluating the SL-RAT condition assessment. The SL-DOG
uses the reassessed pipe length to reevaluate the condition assessment.
2. Verify the utility's pipe segment ID associated with the SL-RAT condition assessment.
The SL-RAT algorithm requires an estimate of the segment length to conduct its condition assessment.
During the in-field measurement, the operator estimates and enters the pipe length (+/- 50 feet) used in
the initial on-site evaluation. The SL-DOG post-processing allows the reevaluation of the condition
assessment based on an updated pipe length. As an example, if an operator inadvertently enters 50' for
a 250' pipe segment, the actual acoustic condition assessment may be higher than the value reported in
the field on the SL-RAT device. The SL-DOG can correct the condition assessment based on the 250'
length.
Depending on the preventive maintenance policy used by the utility for integrating the SL-RAT condition
assessment, registering the SL-RAT measurement can be an essential element. The SL-RAT measurement
registration requires associating the utility's pipe segment ID (or equivalent ID) to the SL-RAT's
measurement record number. Registration enables the following
1. Identifying the SL-RAT condition assessment within the utility's GIS system
2. SL-RAT condition assessment reevaluated based on the utility's GIS pipe segment length
3. Historical comparative analysis of the SL-RAT condition assessment for the pipe segment.
The SL-DOG verification process is illustrated using the SL-RAT measurements conducted at five pipe
segments during the EPA project study. The five segments are from Galia road as depicted in Figure A-l.
The corresponding SL-RAT in-field measurement data augmented with the SL-DOG evaluation are given
in Table A-l for the five pipe segments. In Table A-l, the measurements are grouped based on the
verified segment ID (column 13) with multiple measurements for each pipe segment. The seven columns
under the "SL-RAT In-Field Measurement Data" heading are data obtained directly from the SL-RAT. The
"Pipe Length" in column 3 is the operator specified pipe length in feet and is used in evaluating the pipe
segment condition assessment given in column 4. This is the SL-RAT condition assessment reported to
the operator in the field based on their estimate of the pipe length.
The first verification stage is based on the SL-DOG automatically reassessing the SL-RAT condition
assessment when the SL-RAT measurement data is uploaded. The reassessment is based on evaluating
A-l
-------
Demonstration ofSL-RA 7™ Report Appendix A
the pipe segment length using the GPS location estimates for the SL-RAT transmitter and receiver
(columns 5 through 8). The GPS based pipe length estimate and the corresponding SL-RAT condition
assessment are given under the heading "GPS Based Evaluation" in Table A-l.
The second verification stage is based on associating the SL-RAT measurement with the utility's segment
ID. This association requires additional information from the utility which identifies the utility's segment
ID based on the upstream and downstream manhole locations for each segment. This can typically be
obtained from the utility's GIS data base as summarized in Table A-2 for the five Galia road pipe
segments. The SL-DOG uses both the SL-RAT measurement data and the utility's GIS data to associate
each segment ID to the recorded measurement. The current SL-DOG mapping algorithm is in beta
development. The segment ID association provided by the SL-DOG mapping for the five Galia road pipe
segments is given under the heading "Mapping Based on GPS & Utility GIS" in Table A-l.
To illustrate the segment ID association, in Figure A-2 the three measurements conducted for pipe
segment 11706002-11707005 are depicted based on the GPS location estimates for the SL-RAT
transmitter and receiver. As with any GPS device, the location estimates are influenced by variations in
relative satellite locations, foliage, weather, and other obstructions affecting signal reception from the
satellites. These variations in signal reception impact the error associated with the location estimate as
illustrated in Figure A-2. For the three measurements, the SL-DOG mapping algorithm correctly
associated the GPS location with the segment ID from the utility's GIS data.
When the SL-RAT GPS location estimates are sufficiently large, an error in segment ID association can
occur. As an example, for the measurement with record number 677, the SL-DOG mapping algorithm
incorrectly associated the measurement to the adjacent pipe segment. To assist in identifying incorrect
segment ID associations, a confidence measure is provided for the SL-DOG mapping (column 11, Table
A-l). A low confidence measure indicates a potential error in segment ID association and/or indicates a
potential error in the manhole locations in the utility's GIS data base.
The third verification stage is based on the recommended use of the SL-DOG mapping algorithm as a
verification tool for the operator's measurement registration. The operator measurement registration is
the operator's association between the utility's segment ID and the SL-RAT measurement record
number recorded at the time of the measurement. During the SL-DOG automated post-processing,
discrepancies between the operator measurement registration and the SL-DOG's mapping can be
flagged and corrected based on visual inspection. For the five Galia road pipe segments, the last three
columns in Table A-l contain the verified segment ID association (column 13) for each measurement.
Based on this association, the GIS pipe segment length (column 14) was used to reevaluate the SL-RAT
condition assessment for the pipe segment (column 15).
A-2
-------
Demonstration oj'SL-RAT™Report
Appendix A
Figure A-l. Five Galia road pipe segments used to illustrate the SL-RAT condition assessment
verification. Call out box for pipe segment 11706002-11707005 indicates the measurement ID and the
condition assessment score for the three SL-RAT measurements conducted for the pipe segment during
the EPA project.
A-3
-------
Demonstration oj'SL-RAT™Report
Appendix A
Table A-l. SL-RAT in-field measurement data augmented with the SL-DOG evaluation for the five Galia road pipe segments.
SL-RAT Field Measurements & Data
Rec
Num
620
621
673
628
677
627
676
626
675
708
622
674
710
619
672
Measurement
Date Time
1/28/2013 11:43
1/28/201311:46
4/16/201311:22
1/31/2013 12:02
4/16/2013 11:43
1/31/2013 11:53
4/16/2013 11:39
1/31/201311:41
4/16/201311:33
5/3/2013 16:58
1/28/2013 12:34
4/16/2013 11:28
5/3/2013 17:05
1/28/201311:17
4/16/2013 11:16
Pipe
Length
250
250
250
150
250
350
350
350
350
350
250
250
250
150
150
Assess- „ . Rx
Rx Lat
ment Long
0
0
7
10
9
7
8
5
8
9
8
9
9
9
9
39.133
39.133
39.133
39.135
39.135
39.134
39.134
39.134
39.133
39.133
39.133
39.133
39.133
39.132
39.132
-84.698
-84.698
-84.698
-84.694
-84.695
-84.695
-84.696
-84.696
-84.696
-84.697
-84.697
-84.697
-84.697
-84.698
-84.699
TxLat
39.132
39.132
39.132
39.134
39.134
39.134
39.133
39.133
39.133
39.134
39.133
39.133
39.133
39.132
39.132
Tx Long
-84.698
-84.698
-84.698
-84.695
-84.695
-84.696
-84.696
-84.697
-84.697
-84.696
-84.698
-84.698
-84.698
-84.699
-84.698
GPS Based
Evaluation
Pipe
Length
236
236
191
188
233
375
356
218
275
350
262
155
368
91
166
Assess-
ment
0
0
7
10
9
7
8
4
8
9
8
9
10
9
9
Mapping Based
on GPS & Utility
GIS
Confi-
dence
100
100
100
100
1
97
5
52
7
93
100
50
95
100
100
Segment
ID
11707005-
11702001
11707005-
11702001
11707005-
11702001
11706005-
11706004
11706004-
11706003
11706004-
11706003
11706004-
11706003
11706003-
11706002
11706003-
11706002
11706003-
11706002
11706002-
11707005
11706002-
11707005
11706002-
11707005
11702001-
11702002
11702001-
11702002
Verified Data
Registration
Segment
ID
11707005-
11702001
11707005-
11702001
11707005-
11702001
11706005-
11706004
11706005-
11706004
11706004-
11706003
11706004-
11706003
11706003-
11706002
11706003-
11706002
11706003-
11706002
11706002-
11707005
11706002-
11707005
11706002-
11707005
11702001-
11702002
11702001-
11702002
Pipe
Length
251
251
251
1
257
257
401
401
361
361
361
295
295
295
1
121
121
Assess-
ment
0
0
7
10
9
7
8
5
8
9
8
9
9
9
9
A-4
-------
Demonstration oj'SL-RAT™Report
Appendix A
Table A-2. The utility GIS data required by the SL-DOG to associate the pipe segment ID (Name) with the SL-RAT in-field GPS location estimated
by the SL-RAT receiver and transmitter units. GIS data is for the five Galia road pipe segments used to illustrate the SL-DOG verification process.
Segment Name
11707005-11702001
11706005-11706004
11706004-11706003
11706003-11706002
11706002-11707005
11702001-11702002
Man Hole 1 ID
11707005
11706005
11706004
11706003
11706002
11702001
Man Hole 2 ID
11702001
11706004
11706003
11706002
11707005
11702002
Length (feet)
251
257
401
361
295
121
MH 1 Latitude
39.1328
39.1348
39.1344
39.1336"
39.1330
39.1322"
MH 1 Longitude
-84.6979
84.6941
-84.6949
84.6959
-84.6969
84.6984
MH 2 Latitude
39.1322
39.1344
39.1336
39.1330"
39.1328
39.1320"
MH 2 Longitude
-84.6984
84.6949
-84.6959
84.6969
-84.6979
84.6987
A-5
-------
Demonstration oj'SL-RAT™Report
Appendix A
Figure A-2. GPS mapping for the three SL-RAT condition assessments conducted at Galia road pipe
segment 11706002-11707005.
A-6
-------
Demonstration oj'SL-RAT™Report
Appendix B
APPENDIX B-STUDY AREA FIGURES
Pipe Size (in.) Material Type
Figure B-l. Galia Drive
Sewer Pipe Location.
B-l
-------
Demonstration oj'SL-RAT™Report
Appendix B
Legen
Rpe Size (in.) Mierial Type
Figure B-2. Hunt Road
Sewer Pipe Location.
B-2
-------
Demonstration oj'SL-RAT™Report
Appendix B
Pipe Size (in.) Material Type
Figure B-3. Greenhills
Sewer Pipe Location
B-3
------- |